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Diabetes Mellitus in Pregnancy: Implications for Obstetric Anesthesia. Diabetes in pregnancy is a common obstetric comorbidity that increases the risks of pregnancy-specific complications. The authors describe in this review how understanding ambulatory use of insulin can impact peripartum anesthesia care. Additionally, they describe the appropriate delivery, dosing, and timing of insulin during birth as relevant for anesthesiologists. They discuss the indications and limitations of technologies such as continuous glucose monitors and insulin pumps in pregnancy, and describe their relevance and appropriate management in the perioperative and peripartum period. Finally, the authors review the unique complication of euglycemic diabetic ketoacidosis and provide appropriate management strategies, as anesthesiologists may be in a position to recognize this complication that could otherwise be overlooked.

Appropriate classification of diabetes in pregnancy is necessary for risk stratification, defining antepartum and peripartum treatment strategies and patient counseling. DM in pregnancy is classified as either preexisting (type 1 [TIDM] or type 2 [T2DM]) or having developed during pregnancy (gestational DM [GDM]).6,7,18 GDM accounts for 85 to 90% of diabetes in pregnancy. It can be difficult to differentiate between those individuals who had preexisting (but unrecognized) T2DM and those individuals who only developed diabetes due to the hormonal changes of pregnancy (GDM), so from a practical standpoint, these two entities are often treated similarly. Obstetricians typically further subclassify GDM by whether or not mediation is needed to maintain glucose in the normal range: GDM,A1 means hyperglycemia is managed through dietary and lifestyle changes alone (approximately 85% of GDM), whereas GDM,A2 means there has been the addition of medication such as insulin or oral hypoglycemic (approximately 15% of GDM). Table 1 providers further details on the classification of diabetes in pregnancy.6,7,18 Classification of Diabetes Mellitus in Pregnancy Note that exceptionally rare causes of diabetes in pregnancy such as genetic defects of beta cells or insulin function and acquired defects of the exocrine pancreas such as pancreatitis or trauma are not categorized here.

Appropriate classification of diabetes in pregnancy is necessary for risk stratification, defining antepartum and peripartum treatment strategies and patient counseling. DM in pregnancy is classified as either preexisting (type 1 [TIDM] or type 2 [T2DM]) or having developed during pregnancy (gestational DM [GDM]).6,7,18 GDM accounts for 85 to 90% of diabetes in pregnancy. It can be difficult to differentiate between those individuals who had preexisting (but unrecognized) T2DM and those individuals who only developed diabetes due to the hormonal changes of pregnancy (GDM), so from a practical standpoint, these two entities are often treated similarly. Obstetricians typically further subclassify GDM by whether or not mediation is needed to maintain glucose in the normal range: GDM,A1 means hyperglycemia is managed through dietary and lifestyle changes alone (approximately 85% of GDM), whereas GDM,A2 means there has been the addition of medication such as insulin or oral hypoglycemic (approximately 15% of GDM). Table 1 providers further details on the classification of diabetes in pregnancy.6,7,18 Classification of Diabetes Mellitus in Pregnancy Note that exceptionally rare causes of diabetes in pregnancy such as genetic defects of beta cells or insulin function and acquired defects of the exocrine pancreas such as pancreatitis or trauma are not categorized here. DM, diabetes mellitus; GDM, gestational diabetes mellitus; GDM,A1, diet-controlled gestational diabetes mellitus; GDM,A2, medication-controlled gestational diabetes mellitus; HbA1c, hemoglobin A1c; T1DM, type 1 diabetes mellitus; T2DM, type 2 diabetes mellitus.

Other than for those rare patients who had no prenatal care and present only at the time of labor or with an acute complication in pregnancy, anesthesiologists typically have the benefit of caring for patients who have already been diagnosed and categorized by diabetes type. This is because current consensus practice guidelines from a variety of sources—including the U.S. Preventive Services Task Force (Rockville, Maryland), the American College of Obstetrics and Gynecology (ACOG; Washington, D.C.), and the American Diabetes Association (ADA; Arlington, Virginia)—recommend universal screening for GDM at 24 to 28 weeks of gestation for all individuals with pregnancy without known preexisting diabetes.18–20

Task Force (Rockville, Maryland), the American College of Obstetrics and Gynecology (ACOG; Washington, D.C.), and the American Diabetes Association (ADA; Arlington, Virginia)—recommend universal screening for GDM at 24 to 28 weeks of gestation for all individuals with pregnancy without known preexisting diabetes.18–20 ACOG also suggests that patients with clear risk factors for undiagnosed T2DM (such as obesity, polycystic ovary syndrome, or certain ethnic groups) may be screened for diabetes earlier than 24 weeks of gestation. Other groups such as the ADA are even more aggressive in encouraging universal early screening to identify patients who may have preexisting diabetes before pregnancy or abnormal glucose metabolism early in pregnancy. The 2025 ADA Standards of Practice suggest that for any individuals not known to have diabetes before pregnancy, universal early screening should be considered before 15 weeks of gestation.18 The ADA provides criteria for recognizing abnormal glucose metabolism early in pregnancy, and recommends that a diagnosis of diabetes before 15 weeks of gestation be made the same way as for nonpregnant individuals: by using a hemoglobin A1c (A1c), fasting plasma glucose, or a 2-h (75-g) glucose tolerance test. An A1c 6.5% or greater, fasting glucose 126 mg/dl or greater, or 2-h glucose tolerance test 200 mg/dl or greater indicates the presence of preexisting diabetes (most likely T2DM). In our own practice, we have recommended universal A1c at the initial prenatal visit (before 15 weeks of gestation) as a screen for individuals without preexisting diabetes. Of note, A1c decreases throughout gestation due to increased red blood cell turnover, making it challenging to use as a diagnostic tool after 15 weeks of gestation.21 Thus, if screening for diabetes is not performed early as per ADA suggestion but only at 24 to 28 weeks of gestation as per ACOG guidelines for all individuals without preexisting diabetes, such screening should be done with a glucose load test or an oral glucose tolerance test, not A1c. The relative merits and flaws of various screening tests and diagnostic criteria for GDM are well summarized in the ADA Standards of Care in Diabetes but are beyond the scope of this review.18 Patients with T1DM are almost always recognized before pregnancy.

Irrespective of diabetes type, a key goal of management is to maintain strict euglycemia. Maternal diabetes increases the risks of pregnancy-specific complications such as stillbirth, preeclampsia, shoulder dystocia, and cesarean birth, all of which may increase the likelihood of needing comanagement by an anesthesia provider during birth. These adverse outcomes in pregnancy are linearly correlated with the degree of hyperglycemia,22 and insulin therapy in the latter portion of pregnancy has been shown in two large randomized controlled trials (RCTs) to improve a variety of pregnancy outcomes.23,24 Key to achieving this is regular glucose monitoring combined with insulin administration if needed to manage hyperglycemia. In this next section, we will review considerations related to ambulatory management of diabetes.

in two large randomized controlled trials (RCTs) to improve a variety of pregnancy outcomes.23,24 Key to achieving this is regular glucose monitoring combined with insulin administration if needed to manage hyperglycemia. In this next section, we will review considerations related to ambulatory management of diabetes. Glycemic targets and timing of glucose assessments differ in pregnant compared to nonpregnant populations. Current ACOG and ADA guidelines recommend targeting a fasting glucose value of less than 95 mg/dl, and a postprandial glucose value of less than 140 mg/dl at 1 h after a meal and less than 120 mg/dl 2 h after a meal.6,7,25 These blood glucose goals are lower than values recommended for many nonpregnant adults with diabetes for whom a range of 80 to 130 mg/dl is an acceptable fasting capillary blood glucose and less than 180 mg/dl is targeted for the peak postprandial capillary blood glucose.26 It is important to note how the relationship between the risks and benefits of tight blood glucose control varies for pregnant versus nonpregnant individuals. For nonpregnant patients, the aim of controlling blood glucose levels in the outpatient setting is primarily to reduce long-term microvascular and cardiovascular risks. The relative benefits of very tight glucose control may therefore be outweighed by the acute risk of hypoglycemia. This calculus is different for pregnant individuals, where normal blood glucose levels are naturally lower than for nonpregnant individuals, and where the primary aim of tightly controlling blood glucose levels is to reduce the risk of fetal and obstetric complications.

be outweighed by the acute risk of hypoglycemia. This calculus is different for pregnant individuals, where normal blood glucose levels are naturally lower than for nonpregnant individuals, and where the primary aim of tightly controlling blood glucose levels is to reduce the risk of fetal and obstetric complications. Postprandial monitoring is favored in pregnancy due to evidence that postprandial adjustments led to higher insulin dosing, lower A1c levels at birth, and lower rates of cesarean birth or fetuses that are large for gestational age.27 Note also that this differs from management in nonpregnant individuals where premeal monitoring predominates, although for individuals with T1DM or those with basal-bolus insulin, the addition of premeal correction insulin in pregnancy may help better achieve postprandial glucose targets.

e large for gestational age.27 Note also that this differs from management in nonpregnant individuals where premeal monitoring predominates, although for individuals with T1DM or those with basal-bolus insulin, the addition of premeal correction insulin in pregnancy may help better achieve postprandial glucose targets. The 140 mg/dl postmeal target originates from small studies that evaluated the average postprandial glucose in healthy individuals.6,7,25 However, more recent efforts to characterize normal glycemic variation in heathy pregnant individuals using continuous glucose monitoring (CGM) devices suggest that normal glucose values in pregnancy are even lower than these targets, with average fasting values documented to be around 88 mg/dl, and average 1-h postprandial glucose values of 126 mg/dl.28 A large RCT investigating glucose targets on perinatal outcomes is ongoing,29 but in the meantime, a key take-home point for anesthesiologists is that target glucose levels in pregnancy should likely be as close to normal as possible, including in the peripartum period.

e 1-h postprandial glucose values of 126 mg/dl.28 A large RCT investigating glucose targets on perinatal outcomes is ongoing,29 but in the meantime, a key take-home point for anesthesiologists is that target glucose levels in pregnancy should likely be as close to normal as possible, including in the peripartum period. Self-monitoring of blood glucose is considered a mainstay of diabetes management in pregnancy. Typically, pregnant individuals with diabetes are asked to keep a journal of glucose levels recorded at four timepoints throughout the day: a morning level before eating, and then at 1 or 2 h postprandially after each meal.7,25 These patient-reported values or monitoring logs are used to guide decisions related to insulin dosing. While there are known discrepancies between self-reported and meter-validated values,30,31 advances in glucose monitoring platforms enable direct monitoring of meter-recorded glucose values32,33 and therefore potentially make it less likely that falsely reported values drive clinical decision-making. Recent work shows that an increase in self-monitoring of blood glucose is associated with improvements in clinical outcomes in pregnancy. Specifically, it has been found that for every 10% increase in adherence to testing recommendations, the odds of cesarean birth, neonatal hypoglycemia, and large-for-gestational-age fetuses decrease by 15 to 20%.34 Because of this evidence that increased monitoring can be associated with improved outcomes, there is growing interest in use of CGM devices in pregnancy.35,36

rease in adherence to testing recommendations, the odds of cesarean birth, neonatal hypoglycemia, and large-for-gestational-age fetuses decrease by 15 to 20%.34 Because of this evidence that increased monitoring can be associated with improved outcomes, there is growing interest in use of CGM devices in pregnancy.35,36 For individuals with T1DM, use of a CGM device is recommended by the ADA and the British National Institute for Health and Care Excellence (London, United Kingdom).25,37 This is based on documented improvement in recognition of hypoglycemia and trends toward improved clinical outcomes.38

rease in adherence to testing recommendations, the odds of cesarean birth, neonatal hypoglycemia, and large-for-gestational-age fetuses decrease by 15 to 20%.34 Because of this evidence that increased monitoring can be associated with improved outcomes, there is growing interest in use of CGM devices in pregnancy.35,36 For individuals with T1DM, use of a CGM device is recommended by the ADA and the British National Institute for Health and Care Excellence (London, United Kingdom).25,37 This is based on documented improvement in recognition of hypoglycemia and trends toward improved clinical outcomes.38 The combination of a CGM device paired with both a wearable insulin pump and a mathematical control algorithm that instructs the pump to automatically adjust basal rate of insulin and administer corrective bolus doses based on real-time interstitial fluid glucose levels is called a hybrid closed loop system (HCL).39 Manual insulin dosing is typically still needed with HCL, for example around mealtimes, but the overall burden of user input and calculating insulin dosages may be decreased with HCL. Currently available HCLs typically combine interoperable components from different manufacturers (i.e., a CGM device and computer algorithm from one company may be integrated with an automated insulin pump from another company; some patients may use a third-party or open-source phone app to analyze data from a CGM device and control the rate of insulin delivery from a compatible insulin pump; fig. 1). A recent large open-label, multicenter, randomized parallel group trial demonstrated significant improvement in maternal glycemic control during pregnancy complicated by T1DM with use of a CGM device as part of an HCL, as compared to use of a CGM device with standard insulin delivery methods (i.e., by means of multiple daily injections or a standard insulin pump).40 This has led to significant enthusiasm for potentially expanding use of CGM devices and HCL into other populations of pregnant patients with diabetes.

as part of an HCL, as compared to use of a CGM device with standard insulin delivery methods (i.e., by means of multiple daily injections or a standard insulin pump).40 This has led to significant enthusiasm for potentially expanding use of CGM devices and HCL into other populations of pregnant patients with diabetes. Schematic of wearable technology to create a hybrid closed loop system for diabetes management in pregnancy. Use of CGM devices is not currently recommended in GDM, in part because they have not been shown to clearly improve either maternal or fetal outcomes relative to intermittent self glucose monitoring,41,42 but ongoing RCTs may change these recommendations in the future.43,44 For individuals with T2DM, emerging data suggest that CGM devices may be associated with decreased neonatal morbidity, fewer preterm births, and decreased neonatal intensive care unit admissions45; however, study results are inconsistent.46 Whether or not formal consensus guidelines actively recommend their use, the popularity and use of CGM devices and HCL have increased enough that anesthesiologists should maintain a basic understanding of their functionality, as many pregnant individuals are likely to present for anesthetic care with the devices still in situ. Basic information on common CGM devices is provided later in this review and in table 2.48–50,52 Features of Three Current Continuous Glucose Monitors Commonly Used in Pregnancy

Use of CGM devices is not currently recommended in GDM, in part because they have not been shown to clearly improve either maternal or fetal outcomes relative to intermittent self glucose monitoring,41,42 but ongoing RCTs may change these recommendations in the future.43,44 For individuals with T2DM, emerging data suggest that CGM devices may be associated with decreased neonatal morbidity, fewer preterm births, and decreased neonatal intensive care unit admissions45; however, study results are inconsistent.46 Whether or not formal consensus guidelines actively recommend their use, the popularity and use of CGM devices and HCL have increased enough that anesthesiologists should maintain a basic understanding of their functionality, as many pregnant individuals are likely to present for anesthetic care with the devices still in situ. Basic information on common CGM devices is provided later in this review and in table 2.48–50,52 Features of Three Current Continuous Glucose Monitors Commonly Used in Pregnancy Note that continuous glucose monitors are separate products from automated insulin delivery devices (e.g., wearable insulin pumps), which are not described here (with the exception of the Medtronic MiniMed 780G, which is part of a closed-loop insulin delivery system with the Medtronic Guardian 4 sensor and transmitter). Also note that older models or other brands not listed here may require calibration with finger-prick capillary glucose levels, have longer warm-up periods, be more affected by acetaminophen, or not have integration with wearable insulin pumps. Newer devices than those listed here have been announced in 2024 and 2025. Information was gathered from FDA approval forms and device user manuals or safety booklets. Dexcom G7 (Dexcom, Inc., USA), Abbott FreeStyle Libre 3 (Abbott Diabetes Care, USA), Medtronic Guardian 4 Sensor and Transmitter (Medtronic, USA).

umps. Newer devices than those listed here have been announced in 2024 and 2025. Information was gathered from FDA approval forms and device user manuals or safety booklets. Dexcom G7 (Dexcom, Inc., USA), Abbott FreeStyle Libre 3 (Abbott Diabetes Care, USA), Medtronic Guardian 4 Sensor and Transmitter (Medtronic, USA). CGM, continuous glucose monitoring; CT, computed tomography; FDA, Food and Drug Administration; GDM, gestational diabetes mellitus; HCL, hybrid closed loop system; MRI, magnetic resonance imaging; T1DM, type 1 diabetes mellitus; T2DM, type 2 diabetes mellitus.

umps. Newer devices than those listed here have been announced in 2024 and 2025. Information was gathered from FDA approval forms and device user manuals or safety booklets. Dexcom G7 (Dexcom, Inc., USA), Abbott FreeStyle Libre 3 (Abbott Diabetes Care, USA), Medtronic Guardian 4 Sensor and Transmitter (Medtronic, USA). CGM, continuous glucose monitoring; CT, computed tomography; FDA, Food and Drug Administration; GDM, gestational diabetes mellitus; HCL, hybrid closed loop system; MRI, magnetic resonance imaging; T1DM, type 1 diabetes mellitus; T2DM, type 2 diabetes mellitus. Insulin is required in individuals with T1DM and is recommended as the first-line therapy for individuals with T2DM and GDM who require medication to achieve euglycemia. Insulin use is associated with a good safety profile for both mother and fetus and has strong evidence of efficacy. The oral agents metformin and glyburide were historically widely prescribed in pregnancy, and in the United States especially, there has been a dramatic recent increase in the prevalence of pregnant women exposed to other noninsulin glucose-lowering agents such as glucagon-like peptide-1 (GLP-1) receptor agonists early in pregnancy.51 However, none of these noninsulin agents are currently recommended by either the ADA or ACOG to treat any form of diabetes in pregnancy due to risks of severe prolonged neonatal hypoglycemia with glyburide, long-term metabolic health concerns of offspring with metformin, and impaired fetal growth with GLP-1 receptor agonists. These and other noninsulin antihyperglycemic drugs should be stopped preconception, or as soon as pregnancy is detected. Given current guidelines, it is unlikely that pregnant individuals presenting for anesthesia care will be taking noninsulin glucose-lowering medications.

ed fetal growth with GLP-1 receptor agonists. These and other noninsulin antihyperglycemic drugs should be stopped preconception, or as soon as pregnancy is detected. Given current guidelines, it is unlikely that pregnant individuals presenting for anesthesia care will be taking noninsulin glucose-lowering medications. In the ambulatory setting, insulin can only be administered subcutaneously. A recent review highlighted strategies for ambulatory insulin management in pregnancy.3 Subcutaneous insulin is typically administered as basal and bolus doses. Basal insulin (such as glargine or Neutral Protamine Hagedorn insulin) provides longer-lasting insulin effects, and bolus insulin (such as aspart or lispro) provides shorter-term impacts to help with postmeal hyperglycemia. The pharmacokinetics of different insulin formulations are given in table 3.7,53 As described later, anesthesiologists are most likely to encounter patients on continuous IV insulin infusions who have already been transitioned from subcutaneous insulin, because a continuous infusion of regular insulin is preferred for parturients in active labor. Examples of Insulin Commonly Used in Pregnancy Note that regular insulin can be administered either subcutaneously or intravenously, and that the pharmacokinetics of regular insulin administered subcutaneously are not described in this table. The onset and peak effects of regular insulin administered as a continuous infusion (as opposed to intermittent bolus) differ from the values listed in this table.53 NPH, Neutral Protamine Hagedorn

Note that regular insulin can be administered either subcutaneously or intravenously, and that the pharmacokinetics of regular insulin administered subcutaneously are not described in this table. The onset and peak effects of regular insulin administered as a continuous infusion (as opposed to intermittent bolus) differ from the values listed in this table.53 NPH, Neutral Protamine Hagedorn Although anesthesiologists do not typically adjust insulin regimens for patients outside the operating room, they should be aware of a patient’s current insulin dose and have a general understanding of how insulin dosing is adjusted. For instance, we suggest following the example set at many institutions, where the most recent point-of-care blood glucose measurement is mandatorily mentioned in a procedural “Time Out” before a labor neuraxial technique. Insulin may need to be adjusted (typically, decreased) in response to the glucose value after initiation of the neuraxial anesthetic, as maternal stress response to labor is decreased with anesthesia. Anesthesiologists should be prepared to manage the IV insulin infusion during a cesarean birth, and may need to make a decision about what rate to start an infusion at when transitioning a patient from intermittent subcutaneous to continuous IV insulin. For insulin infusions used during birth, most hospitals have standard algorithms that typically start at a low rate of infusion and increase as needed based on glucose values (Supplemental Digital Content, https://links.lww.com/ALN/D985).54

ransitioning a patient from intermittent subcutaneous to continuous IV insulin. For insulin infusions used during birth, most hospitals have standard algorithms that typically start at a low rate of infusion and increase as needed based on glucose values (Supplemental Digital Content, https://links.lww.com/ALN/D985).54 Due to a recognized increased risk of stillbirth among pregnant individuals who require insulin to manage their diabetes, induction of labor is often recommended before 40 weeks of pregnancy for women with T1DM, T2DM, and GDM,A2.6,7 Delivery between 39 weeks 0 days and 39 weeks 6 days, is preferred, but earlier birth may be considered at 36 weeks 0 days to 38 weeks 6 days in individuals with preexisting diabetes and “poor glucose control” or certain other complications.7,55 Similarly, for patients with uncomplicated GDM,A2, ACOG notes that birth at 37 weeks 0 days to 38 weeks 6 days may be “justified” after balancing risks of prematurity with risks of stillbirth.7 For patients with “poorly controlled” GDM,A2, even late preterm delivery can be considered per ACOG.7 However, no consensus definition for “poor glucose control” necessitating early birth exists, and we have found significant variability in the rationale provided for early birth recommendations.56 Given that birth may be indicated before the onset of labor, many individuals with perinatal diabetes will undergo an induction of labor or scheduled cesarean birth and thus require anesthesia care.

Glycemic targets and timing of glucose assessments differ in pregnant compared to nonpregnant populations. Current ACOG and ADA guidelines recommend targeting a fasting glucose value of less than 95 mg/dl, and a postprandial glucose value of less than 140 mg/dl at 1 h after a meal and less than 120 mg/dl 2 h after a meal.6,7,25 These blood glucose goals are lower than values recommended for many nonpregnant adults with diabetes for whom a range of 80 to 130 mg/dl is an acceptable fasting capillary blood glucose and less than 180 mg/dl is targeted for the peak postprandial capillary blood glucose.26 It is important to note how the relationship between the risks and benefits of tight blood glucose control varies for pregnant versus nonpregnant individuals. For nonpregnant patients, the aim of controlling blood glucose levels in the outpatient setting is primarily to reduce long-term microvascular and cardiovascular risks. The relative benefits of very tight glucose control may therefore be outweighed by the acute risk of hypoglycemia. This calculus is different for pregnant individuals, where normal blood glucose levels are naturally lower than for nonpregnant individuals, and where the primary aim of tightly controlling blood glucose levels is to reduce the risk of fetal and obstetric complications.

Self-monitoring of blood glucose is considered a mainstay of diabetes management in pregnancy. Typically, pregnant individuals with diabetes are asked to keep a journal of glucose levels recorded at four timepoints throughout the day: a morning level before eating, and then at 1 or 2 h postprandially after each meal.7,25 These patient-reported values or monitoring logs are used to guide decisions related to insulin dosing. While there are known discrepancies between self-reported and meter-validated values,30,31 advances in glucose monitoring platforms enable direct monitoring of meter-recorded glucose values32,33 and therefore potentially make it less likely that falsely reported values drive clinical decision-making. Recent work shows that an increase in self-monitoring of blood glucose is associated with improvements in clinical outcomes in pregnancy. Specifically, it has been found that for every 10% increase in adherence to testing recommendations, the odds of cesarean birth, neonatal hypoglycemia, and large-for-gestational-age fetuses decrease by 15 to 20%.34 Because of this evidence that increased monitoring can be associated with improved outcomes, there is growing interest in use of CGM devices in pregnancy.35,36 For individuals with T1DM, use of a CGM device is recommended by the ADA and the British National Institute for Health and Care Excellence (London, United Kingdom).25,37 This is based on documented improvement in recognition of hypoglycemia and trends toward improved clinical outcomes.38

Self-monitoring of blood glucose is considered a mainstay of diabetes management in pregnancy. Typically, pregnant individuals with diabetes are asked to keep a journal of glucose levels recorded at four timepoints throughout the day: a morning level before eating, and then at 1 or 2 h postprandially after each meal.7,25 These patient-reported values or monitoring logs are used to guide decisions related to insulin dosing. While there are known discrepancies between self-reported and meter-validated values,30,31 advances in glucose monitoring platforms enable direct monitoring of meter-recorded glucose values32,33 and therefore potentially make it less likely that falsely reported values drive clinical decision-making. Recent work shows that an increase in self-monitoring of blood glucose is associated with improvements in clinical outcomes in pregnancy. Specifically, it has been found that for every 10% increase in adherence to testing recommendations, the odds of cesarean birth, neonatal hypoglycemia, and large-for-gestational-age fetuses decrease by 15 to 20%.34 Because of this evidence that increased monitoring can be associated with improved outcomes, there is growing interest in use of CGM devices in pregnancy.35,36 For individuals with T1DM, use of a CGM device is recommended by the ADA and the British National Institute for Health and Care Excellence (London, United Kingdom).25,37 This is based on documented improvement in recognition of hypoglycemia and trends toward improved clinical outcomes.38 The combination of a CGM device paired with both a wearable insulin pump and a mathematical control algorithm that instructs the pump to automatically adjust basal rate of insulin and administer corrective bolus doses based on real-time interstitial fluid glucose levels is called a hybrid closed loop system (HCL).39 Manual insulin dosing is typically still needed with HCL, for example around mealtimes, but the overall burden of user input and calculating insulin dosages may be decreased with HCL. Currently available HCLs typically combine interoperable components from different manufacturers (i.e., a CGM device and computer algorithm from one company may be integrated with an automated insulin pump from another company; some patients may use a third-party or open-source phone app to analyze data from a CGM device and control the rate of insulin delivery from a compatible insulin pump; fig. 1). A recent large open-label, multicenter, randomized parallel group trial demonstrated significant improvement in maternal glycemic control during pregnancy complicated by T1DM with use of a CGM device as part of an HCL, as compared to use of a CGM device with standard insulin delivery methods (i.e., by means of multiple daily injections or a standard insulin pump).40 This has led to significant enthusiasm for potentially expanding use of CGM devices and HCL into other populations of pregnant patients with diabetes.

Insulin is required in individuals with T1DM and is recommended as the first-line therapy for individuals with T2DM and GDM who require medication to achieve euglycemia. Insulin use is associated with a good safety profile for both mother and fetus and has strong evidence of efficacy. The oral agents metformin and glyburide were historically widely prescribed in pregnancy, and in the United States especially, there has been a dramatic recent increase in the prevalence of pregnant women exposed to other noninsulin glucose-lowering agents such as glucagon-like peptide-1 (GLP-1) receptor agonists early in pregnancy.51 However, none of these noninsulin agents are currently recommended by either the ADA or ACOG to treat any form of diabetes in pregnancy due to risks of severe prolonged neonatal hypoglycemia with glyburide, long-term metabolic health concerns of offspring with metformin, and impaired fetal growth with GLP-1 receptor agonists. These and other noninsulin antihyperglycemic drugs should be stopped preconception, or as soon as pregnancy is detected. Given current guidelines, it is unlikely that pregnant individuals presenting for anesthesia care will be taking noninsulin glucose-lowering medications.

Due to a recognized increased risk of stillbirth among pregnant individuals who require insulin to manage their diabetes, induction of labor is often recommended before 40 weeks of pregnancy for women with T1DM, T2DM, and GDM,A2.6,7 Delivery between 39 weeks 0 days and 39 weeks 6 days, is preferred, but earlier birth may be considered at 36 weeks 0 days to 38 weeks 6 days in individuals with preexisting diabetes and “poor glucose control” or certain other complications.7,55 Similarly, for patients with uncomplicated GDM,A2, ACOG notes that birth at 37 weeks 0 days to 38 weeks 6 days may be “justified” after balancing risks of prematurity with risks of stillbirth.7 For patients with “poorly controlled” GDM,A2, even late preterm delivery can be considered per ACOG.7 However, no consensus definition for “poor glucose control” necessitating early birth exists, and we have found significant variability in the rationale provided for early birth recommendations.56 Given that birth may be indicated before the onset of labor, many individuals with perinatal diabetes will undergo an induction of labor or scheduled cesarean birth and thus require anesthesia care.

The current recommendation from ACOG is that glucose levels should be maintained between 70 and 110 mg/dl during active labor.6,7 This guideline is based on the premise that stringent glucose management during labor may reduce rates of neonatal hypoglycemia, which occurs in up to 50% of neonates born to individuals with perinatal diabetes.57 It is presumed that maternal hyperglycemia can lead to fetal hyperinsulinemia, and if the fetus has acquired a dependence on maternal hyperglycemia over time, sudden withdrawal of maternal glucose at the time of birth contributes to neonatal hypoglycemia.4 In practice, achieving tight glycemic control often involves the use of insulin infusions, which may be supplemented with dextrose-containing fluids to stabilize maternal glucose levels.

n maternal hyperglycemia over time, sudden withdrawal of maternal glucose at the time of birth contributes to neonatal hypoglycemia.4 In practice, achieving tight glycemic control often involves the use of insulin infusions, which may be supplemented with dextrose-containing fluids to stabilize maternal glucose levels. Recent studies have begun to challenge the notion that intrapartum glucose levels are a significant determinant of neonatal hypoglycemia. Systematic reviews imply that factors other than maternal glucose levels at the time of delivery—such as antenatal glycemic control as assessed by A1c, preterm delivery, and large infant size—may play a more critical role in the development of neonatal hypoglycemia.58,59 Two recent RCTs evaluating liberal versus permissive strategies of intrapartum glucose management or glucose targets in active labor (e.g., a glucose target of 60 to 100 mg/dl vs. a more liberal target of 60 to 120 mg/dl) did not show differences in initial neonatal glucose.60,61 Nonetheless, it is our opinion that anesthesiologists managing insulin during cesarean birth should continue to follow current ACOG recommendations and target glucose levels of 70 to 110 mg/dl.

et of 60 to 100 mg/dl vs. a more liberal target of 60 to 120 mg/dl) did not show differences in initial neonatal glucose.60,61 Nonetheless, it is our opinion that anesthesiologists managing insulin during cesarean birth should continue to follow current ACOG recommendations and target glucose levels of 70 to 110 mg/dl. Pregnant patients with T2DM and GDM,A2 who are eating during their hospitalization are typically monitored in the same fashion as before hospitalization: a morning fasting fingerstick glucose level is obtained before eating, and then postprandial glucose levels are subsequently checked at 1 or 2 h after meals. Patients who have been instructed to have nothing by mouth (non per os [NPO]) typically have glucose levels checked every 4 h. Just as there has been a significant increase in the utilization of CGM devices during pregnancy for outpatients, there is significant interest and exploration in the use of CGM devices during inpatient management of labor. Although CGM devices are not approved by the U.S. Food and Drug Administration (Silver Spring, Maryland) for inpatient use,62 a number of institutions have developed protocols for their use, and there is at least one study evaluating the use of CGM devices on management of glucose in labor.63 Anesthesiologists should maintain a basic understanding of the functionality of CGM devices, as many pregnant individuals are likely to present for anesthetic care with the devices still in situ, and the presence of a CGM device may impact patient positioning, draping, and use of warming devices.

of glucose in labor.63 Anesthesiologists should maintain a basic understanding of the functionality of CGM devices, as many pregnant individuals are likely to present for anesthetic care with the devices still in situ, and the presence of a CGM device may impact patient positioning, draping, and use of warming devices. All available CGM devices consist of a sensor that is typically worn on an arm—attached with a strong adhesive and with a thin transcutaneous monofilament—and measures glucose levels in the interstitial fluid rather than capillary blood glucose levels. Modern monitors typically rely on an enzymatic electrochemical reaction. The enzyme glucose oxidase binds with interstitial fluid glucose, producing hydrogen peroxide; an electrical current is generated by the dissociation of hydrogen peroxide, and the strength of this current is proportional to the concentration of glucose in the interstitial fluid, and so can be translated algorithmically into a glucose reading.64 Glucose readings from the sensor are either manually scanned to a dedicated receiver (typically sold separately from the sensors) or automatically wirelessly transmitted (e.g., using Bluetooth [Bluetooth Special Interest Group, USA]) to a receiver or smart cellphone. Glucose may be sampled either every 1 min or every 5 min.

se readings from the sensor are either manually scanned to a dedicated receiver (typically sold separately from the sensors) or automatically wirelessly transmitted (e.g., using Bluetooth [Bluetooth Special Interest Group, USA]) to a receiver or smart cellphone. Glucose may be sampled either every 1 min or every 5 min. Although there can be a discrepancy between the interstitial glucose values that these devices measure and capillary glucose values as measured by finger-prick testing, accuracy is markedly improved with newer devices. Several factors may contribute to inaccurate CGM device readings (fig. 2). Factors contributing to inaccurate readings from a continuous glucose monitor. Direct external pressure over a CGM device can decrease perfusion of the underlying tissue, decreasing interstitial glucose levels. This will lead to a falsely low sensor glucose reading and apparent hypoglycemia.65,66 Although relieving pressure will quickly normalize the CGM device glucose values, an awareness of the possibility of such artifactual “compression hypoglycemia” is especially important for anesthesiologists caring for patients who may be laying on the CGM device without moving during a general or neuraxial anesthetic.

Although relieving pressure will quickly normalize the CGM device glucose values, an awareness of the possibility of such artifactual “compression hypoglycemia” is especially important for anesthesiologists caring for patients who may be laying on the CGM device without moving during a general or neuraxial anesthetic. There also may be a 10- to 20-min lag time between values obtained from fingerstick capillary glucose and CGM device readings. Because glucose moves passively from capillaries into the interstitium, the degree of blood flow, endothelial permeability, and other factors may cause rapid changes in plasma glucose values to not be immediately reflected in the interstitial fluid.67 CGM devices typically account for this by using software modules in their receivers that predict glucose trajectories, to allow early recognition of impending hypoglycemia or hyperglycemia.

y, and other factors may cause rapid changes in plasma glucose values to not be immediately reflected in the interstitial fluid.67 CGM devices typically account for this by using software modules in their receivers that predict glucose trajectories, to allow early recognition of impending hypoglycemia or hyperglycemia. Whereas previous-generation devices typically required calibration by comparing an interstitial value to a concurrently obtained capillary value from a fingerstick, many modern devices available in 2025 are marketed as not requiring such calibration. Sensors are typically effective for 10 to 14 days, again depending on the specific device, and are expensive enough that patients are often resistant to remove them prematurely. Further, newly placed sensors require time to adjust to the patient’s body and produce accurate readings, which means that a new sensor could not be repositioned or replaced just before or just after surgery and be expected to immediately function appropriately. For modern devices, the warmup time may be as short as 30 min to 2 h, but for some older devices, it can take 12 h for activation. Furthermore, patients may wish to avoid finger pricks for capillary glucose monitoring in the hospital. Given these factors, patients may prefer to maintain their CGM device and offer their receivers to their providing teams during hospitalization and even during surgery.

older devices, it can take 12 h for activation. Furthermore, patients may wish to avoid finger pricks for capillary glucose monitoring in the hospital. Given these factors, patients may prefer to maintain their CGM device and offer their receivers to their providing teams during hospitalization and even during surgery. Unfortunately, there is a paucity of evidence on how interstitial fluid is impacted by vasoactive and physiologic changes that occur during surgery; therefore, the accuracy of CGM devices in the operating rooms is not defined. Small studies suggest that CGM device sensors may be less reliable in the operating room and could be affected by electrocautery interference or temperature extremes impacting the underlying enzymatic reaction.68 All available sensors have a limited temperature operating range (generally between 10° and 45°C, depending on manufacturer), and they may malfunction out of these ranges. This makes their use perioperatively potentially problematic for patients who are receiving general or neuraxial anesthesia with normothermia maintained by use of a warming device such as a forced-air warming blanket over the arm or abdomen where the CGM device sensor is located.

ey may malfunction out of these ranges. This makes their use perioperatively potentially problematic for patients who are receiving general or neuraxial anesthesia with normothermia maintained by use of a warming device such as a forced-air warming blanket over the arm or abdomen where the CGM device sensor is located. Acetaminophen, the use of which is recommended by the Enhanced Recovery After Surgery Society (Stockholm, Sweden) as part of a multimodal analgesic regimen for postoperative care after cesarean birth,69 may also affect accuracy of CGM device readings. This is because acetaminophen is metabolized to acetaminophen glucuronide, which some CGM devices mistake for glucose, resulting in falsely high readings. Inaccuracy depends on how much acetaminophen is in the body, is variable, lasts up to 8 h after dosing, and is more likely in those taking more than 4 g acetaminophen per 24 h.70–72 Due to risk of interference or inaccuracy in the perioperative environment, it is our recommendation that if CGM devices are left in situ during anesthetic care, reported values be double-checked with standard fingerstick capillary glucose levels during periods when rapid changes in blood glucose values are expected, such as after administration of glucocorticosteroids or after delivery of the placenta.

recommendation that if CGM devices are left in situ during anesthetic care, reported values be double-checked with standard fingerstick capillary glucose levels during periods when rapid changes in blood glucose values are expected, such as after administration of glucocorticosteroids or after delivery of the placenta. There are no rigorous data to inform guidelines or practice patterns regarding insulin management on the morning of scheduled births. For individuals planning a scheduled cesarean birth or other surgery, insulin dosing is typically reduced before the procedure due to standard NPO policies.6 We suggest that for patients taking multiple daily injections of insulin, basal dosing be reduced by 25 to 50% depending on the type of insulin. For those patients using wearable insulin pumps to administer insulin, we recommend decreasing the basal rate by 25% preoperatively on the morning of surgery and to further decrease it during the postpartum period. Table 4 includes a summary of recommended adjustments to basal insulin regimens before scheduled surgeries in pregnancy. Adjustment to Basal Insulin Dosing for Patients Made NPO in Anticipation of a Scheduled Anesthetic Note that the insulin dosing adjustments demonstrated in this table will typically not be made by anesthesiologists, and this table should not be used to determine intravenous insulin infusion dosing during labor. Basal insulin dosing should be moderately reduced for patients made NPO before surgery, but not discontinued completely. NPH, Neutral Protamine Hagedorn; NPO, non per os.

Note that the insulin dosing adjustments demonstrated in this table will typically not be made by anesthesiologists, and this table should not be used to determine intravenous insulin infusion dosing during labor. Basal insulin dosing should be moderately reduced for patients made NPO before surgery, but not discontinued completely. NPH, Neutral Protamine Hagedorn; NPO, non per os. For individuals admitted for an induction of labor (where NPO policies are typically not as strict, and patients are typically allowed clear liquids throughout active labor), some practice reviews suggest that home insulin can simply be continued at usual dosing. However, we think basal insulin should routinely be decreased by 25%. This is because oral intake of glucose typically decreases during labor relative to usual, even as the metabolic stress of labor creates an increased need for circulating glucose.

ews suggest that home insulin can simply be continued at usual dosing. However, we think basal insulin should routinely be decreased by 25%. This is because oral intake of glucose typically decreases during labor relative to usual, even as the metabolic stress of labor creates an increased need for circulating glucose. The amount of insulin given in response to hyperglycemia is based on the patient’s insulin sensitivity. To simplify correction in the hospital, sliding-scale short-acting insulin is prescribed premeal (or at regular 4-h intervals for patients who are fasting) with predefined or protocolized sliding scales. So-called low-, medium-, high-, or very high-intensity sliding scales are typical of most hospitals, with insulin sensitivity often empirically judged based on a patient’s response to a chosen sliding scale. However, insulin sensitivity can also be calculated as an “insulin sensitivity factor” for each patient based on their total daily dose of insulin. Table 5 includes an example of calculating insulin sensitivity in this fashion. Additional insulin should be administered if betamethasone or dexamethasone is given during admission to accelerate fetal lung maturity,75 as glucocorticosteroids (and also beta-agonists such as terbutaline) can exacerbate maternal hyperglycemia and precipitate diabetic ketoacidosis (DKA). Among individuals with diabetes receiving betamethasone, glucose values are expected to rise at approximately 12 h after administration and peak 48 h after administration before returning to baseline levels approximately 1 week later.76 A recent RCT evaluating maternal glucose after betamethasone exposure showed that at least 80% of individuals without preexisting diabetes had evidence of hyperglycemia based on fasting or postprandial point-of-care testing.77 Interestingly, routine monitoring and treatment in this population do not change rates of neonatal hypoglycemia. Protocols have been proposed to guide empiric adjustment of subcutaneous insulin after betamethasone.78 Once active labor is achieved, transition to an IV insulin infusion is often made with guidance by preestablished hospital-specific protocols. Recent work demonstrates that the use of standard protocols improves maternal glucose control intrapartum (though such protocols may be associated with increases in neonatal hypoglycemia).79

abor is achieved, transition to an IV insulin infusion is often made with guidance by preestablished hospital-specific protocols. Recent work demonstrates that the use of standard protocols improves maternal glucose control intrapartum (though such protocols may be associated with increases in neonatal hypoglycemia).79 Correction Insulin Dosing for Hyperglycemia Patients with T1DM may have used a wearable insulin pump to manage glucose levels in pregnancy before onset of labor, although depending on the device, such use may not be approved by the Food and Drug Administration and so may represent investigational or “off-label” use. It is possible to continue to use the wearable pump throughout labor: a recent RCT showed similar outcomes for individuals using an insulin pump as compared with an insulin infusion in labor,80 and previous retrospective studies provide additional evidence for the safety and feasibility of continuing to use wearable insulin pumps during labor.81 However, use of an insulin pump requires active participation of the patient to manage their pump setting. This may be challenging in some individuals receiving analgesia medications. In such cases, it may be preferable to transition to an IV insulin infusion. It is important to remember that patients with T1DM need insulin for survival, and that if a wearable pump is to be removed or discontinued in labor, there should be no gap in insulin coverage before initiation of the IV infusion.

medications. In such cases, it may be preferable to transition to an IV insulin infusion. It is important to remember that patients with T1DM need insulin for survival, and that if a wearable pump is to be removed or discontinued in labor, there should be no gap in insulin coverage before initiation of the IV infusion. Usually insulin is discontinued after delivery in patients with GDM, as delivery of the placenta markedly decreases insulin demands. Enteral intake (if not contraindicated) or the use of dextrose-containing maintenance fluids can reduce the risk of maternal hypoglycemia in this period if necessary. For patients with T1DM who do not use a wearable insulin pump, or for patients with poorly controlled T2DM that preceded pregnancy, basal/bolus subcutaneous insulin is typically restarted after birth at markedly reduced levels (approximately 20% of prebirth levels or 50% of prepregnancy levels, respectively). This will help reduce the risk of hypoglycemia due to the metabolic demands of lactation. As noted earlier, some stand-alone CGM devices can be paired with an insulin pump; combination systems consisting of both a CGM device and an insulin pump are commercially available. Some of the pumps that can be linked to a CGM device include an automatic mode or a suspend-before-low mode that automatically adjusts or suspends insulin delivery based on CGM device readings to help avoid hypoglycemia.

combination systems consisting of both a CGM device and an insulin pump are commercially available. Some of the pumps that can be linked to a CGM device include an automatic mode or a suspend-before-low mode that automatically adjusts or suspends insulin delivery based on CGM device readings to help avoid hypoglycemia. All wearable insulin pumps consist of a reservoir of rapid-acting insulin (e.g., lispro or aspart) that typically contains enough insulin to last 2 or 3 days, and a thin cannula that is inserted into subcutaneous tissue of the upper arm, abdomen, hip, buttock, or thigh via a spring-retractable needle for delivery of the insulin. The drug reservoir and delivery tubing are separate components in most pump designs: the drug reservoir is housed in a metal-and-plastic battery-powered device about the size of a deck of cards that can be kept in a pocket or clipped to a belt or bra or other piece of clothing. Such pumps typically have a display screen and electronic controls for operation of the pump, and a flexible plastic tube several inches long that delivers insulin from the pump reservoir to the subcutaneous cannula, which is in turn held in place by a small adhesive patch.

to a belt or bra or other piece of clothing. Such pumps typically have a display screen and electronic controls for operation of the pump, and a flexible plastic tube several inches long that delivers insulin from the pump reservoir to the subcutaneous cannula, which is in turn held in place by a small adhesive patch. Other pump options are an integrated single unit where the drug reservoir attaches directly to the patient’s body with a relatively large adhesive patch, and the subcutaneous drug delivery cannula extends directly off the patch-like pump. These “tubeless pumps” or “patch pumps” rely on a wireless remote-control device (or a connected cellphone) to adjust drug dosing and perform data processing tasks. It is important to remember that because wearable insulin pumps exclusively use rapid-acting insulin (administered both as a basal continuous infusion and as bolus injections as necessary), blood glucose levels can rise rapidly in insulin-dependent patients if the pump is removed or the pump site fails. Serum ketones may start to increase as soon as 4 to 6 h after cessation of insulin therapy from a pump. Similarly, if the insulin infusion continues while the patient remains NPO, there is a risk of hypoglycemia. This risk should be managed by providing a dextrose-containing infusion, rather than by holding or discontinuing insulin.

may start to increase as soon as 4 to 6 h after cessation of insulin therapy from a pump. Similarly, if the insulin infusion continues while the patient remains NPO, there is a risk of hypoglycemia. This risk should be managed by providing a dextrose-containing infusion, rather than by holding or discontinuing insulin. It is our opinion that it is almost always appropriate to transition parturients who have a wearable insulin pump and who are admitted to the hospital for delivery to a nurse-managed IV insulin infusion, whether an associated CGM device remains in situ or not. This avoids the risk of euglycemic ketoacidosis, a particular risk for patients with T1DM, in the event insulin administration is interrupted intentionally or due to failure or device malfunction. It also reduces risk of hypoglycemia due to excessive insulin administration.

associated CGM device remains in situ or not. This avoids the risk of euglycemic ketoacidosis, a particular risk for patients with T1DM, in the event insulin administration is interrupted intentionally or due to failure or device malfunction. It also reduces risk of hypoglycemia due to excessive insulin administration. Normal fasting glucose in pregnancy is typically lower than in nonpregnant individuals. Thus, we recommend treating hypoglycemia only when blood glucose less than or equal to 70 mg/dl or patients exhibit symptoms of hypoglycemia.82 For individuals who are able to drink, oral glucose (as from 4 oz of apple juice or other clear liquid carbohydrate beverage) is the preferred treatment. A memorable mnemonic is “the 15-15 rule,” meaning that about 15 g of carbohydrates (the approximate content of 4 oz apple juice) should be administered to treat hypoglycemia, and the blood glucose should be rechecked in 15 min. If the blood glucose is still less than 70 mg/dl, administer another 15 g of carbohydrates until the blood glucose returns to greater than 70 mg/dl on two consecutive checks. For individuals unable to eat, a 50% dextrose injection may be provided: 25 ml D50 (or half a standard premade bag) provides 12.5 g carbohydrate. For individuals without IV access, who cannot swallow, and with glucose less than 50 mg/dl, glucagon 1 mg (1 ml) can be administered intramuscularly or subcutaneously. If there are ongoing risk factors for hypoglycemia, consider use of maintenance fluids containing 5 to 10% dextrose.

bag) provides 12.5 g carbohydrate. For individuals without IV access, who cannot swallow, and with glucose less than 50 mg/dl, glucagon 1 mg (1 ml) can be administered intramuscularly or subcutaneously. If there are ongoing risk factors for hypoglycemia, consider use of maintenance fluids containing 5 to 10% dextrose. Table 6 summarizes considerations for anesthetic and insulin management of patients with diabetes undergoing cesarean birth and receiving either neuraxial or general anesthesia. There is no evidence that either modality should be favored over the other in patients with diabetes—even those who are acutely hyperglycemic—so the same considerations that anesthesiologists use to decide on type of anesthesia for nondiabetic parturients (e.g., urgency of the procedure, coagulation status) are applicable to patients with diabetes. That said, anesthesiologists should remember that the typical comorbidities of diabetes can be present during pregnancy: even young individuals with longstanding poorly controlled T1DM are at an increased risk of renal dysfunction and hypertension (often due to diabetic nephropathy), autonomic neuropathy, hypothyroidism, and ischemic heart disease, all of which may affect general perioperative anesthesia management or planning. For example, patients with preexisting diabetes-related autonomic neuropathy may be especially prone to hypotension with initiation of general or neuraxial anesthesia and resultant sympathetic blockade.83,84 Long-standing T1DM can be associated with glycosylation of collagen in cervical joints and specifically limited head extension at the atlanto-occipital joint, theoretically contributing to difficulties with laryngoscopy, although this concern has not actually been demonstrated in studies.85,86

ympathetic blockade.83,84 Long-standing T1DM can be associated with glycosylation of collagen in cervical joints and specifically limited head extension at the atlanto-occipital joint, theoretically contributing to difficulties with laryngoscopy, although this concern has not actually been demonstrated in studies.85,86 Considerations for Anesthetic and Insulin Management of Patients with Diabetes Undergoing Cesarean Birth under Neuraxial or General Anesthesia GDM, gestational diabetes mellitus; IV, intravenous; T1DM, type 1 diabetes mellitus; T2DM, type 2 diabetes mellitus.

ympathetic blockade.83,84 Long-standing T1DM can be associated with glycosylation of collagen in cervical joints and specifically limited head extension at the atlanto-occipital joint, theoretically contributing to difficulties with laryngoscopy, although this concern has not actually been demonstrated in studies.85,86 Considerations for Anesthetic and Insulin Management of Patients with Diabetes Undergoing Cesarean Birth under Neuraxial or General Anesthesia GDM, gestational diabetes mellitus; IV, intravenous; T1DM, type 1 diabetes mellitus; T2DM, type 2 diabetes mellitus. We recommend that patients receiving IV insulin during labor have two venous access catheters in place—one for fluid administration, and a second dedicated carrier line for insulin and other high-risk infusions. Note that because patients with diabetes are at increased risk for complications such as preeclampsia, it is not uncommon for such patients to require multiple high-risk infusions: for example, oxytocin for induction of labor, magnesium for preeclampsia, dextrose and insulin for glycemic management, and a pressor after initiation of a neuraxial anesthetic. These infusions are at risk of inadvertent bolus during changes in phase of care—such as emergent transfer to an operating room for a stat cesarean birth—and we agree with the unofficial advice from members of the Society for Obstetric Anesthesia and Perinatology (Lexington, Kentucky) Patient Safety Committee, who recommended that insulin and other infusions in labor be given via a three-way connector through dedicated, color-coded tubing without stopcocks or side-injection ports, and should be temporarily discontinued before transport to the operating room.87

and Perinatology (Lexington, Kentucky) Patient Safety Committee, who recommended that insulin and other infusions in labor be given via a three-way connector through dedicated, color-coded tubing without stopcocks or side-injection ports, and should be temporarily discontinued before transport to the operating room.87 The effect of pregnancy on preexisting diabetes-associated gastroparesis is unclear,88 and we are unaware of any firm data as to whether or not additional aspiration precautions should be taken for pregnant women with diabetes above and beyond those precautions already practiced for nondiabetic pregnant patients. The American Society of Anesthesiologists (Schaumburg, Illinois) recently published a “Statement on Oral Intake during Labor.”89 The American Society of Anesthesiologists statement notes that although unlimited electrolyte-containing clear liquid beverages should usually be encouraged and solid foods avoided during active labor, “poorly controlled diabetes” represents a high-risk condition for which additional restrictions may need to be made on oral intake during hospitalization for birth. The document makes no recommendations regarding the consumption of solid food during the prelabor phase for patients admitted for induction of labor, regardless of diabetes status, and at most hospitals, enteral intake is not limited before active labor.

need to be made on oral intake during hospitalization for birth. The document makes no recommendations regarding the consumption of solid food during the prelabor phase for patients admitted for induction of labor, regardless of diabetes status, and at most hospitals, enteral intake is not limited before active labor. It is common to administer 4 to 10 mg IV dexamethasone during a general anesthetic for nausea prophylaxis for both nonpregnant and pregnant patients.73 It may also be used to prolong analgesia and prevent nausea, vomiting, shivering, and hypotension during cesarean birth performed with spinal anesthesia.90 However, a single-center retrospective cohort study demonstrated that antiemetic dexamethasone administered to women with T1DM, T2DM, and GDM before delivery during cesarean birth was associated with a significantly increased rate of neonatal hypoglycemia.91 This is consistent with other studies showing that antenatal glucocorticosteroids given to pregnant patients with diabetes to induce fetal lung maturity in the late preterm can increase the risk of neonatal hypoglycemia and other complications.92,93 It is therefore our opinion that for pregnant patients with diabetes, antiemetic dexamethasone given during a cesarean birth should only be administered after delivery of the fetus.

th diabetes to induce fetal lung maturity in the late preterm can increase the risk of neonatal hypoglycemia and other complications.92,93 It is therefore our opinion that for pregnant patients with diabetes, antiemetic dexamethasone given during a cesarean birth should only be administered after delivery of the fetus. Extrapolating from studies of nonpregnant patients with diabetes who received a single perioperative dose of antiemetic dexamethasone, we presume that the drug is likely to cause transient maternal hyperglycemia if given to pregnant patients with diabetes undergoing nonobstetric surgery (and likely to require treatment with insulin), but is unlikely to be associated with other significant maternal complications such as surgical site infections.94,95 That said, we are unaware of any studies specifically investigating maternal complications of antiemetic dexamethasone in patients with diabetes. Antiemetic dexamethasone has been shown to significantly increase blood glucose levels within 1 h of administration—regardless of whether a 4-mg or 8-mg dose is used—so we recommend rechecking glucose levels at that time point whether used after cesarean section or during nonobstetric surgery.96 It is worth noting that the dose of dexamethasone used to induce fetal lung maturity—four doses of 6 mg intramuscularly given 12 h apart—is significantly higher than the dose used by anesthesiologists for nausea prophylaxis.

levels at that time point whether used after cesarean section or during nonobstetric surgery.96 It is worth noting that the dose of dexamethasone used to induce fetal lung maturity—four doses of 6 mg intramuscularly given 12 h apart—is significantly higher than the dose used by anesthesiologists for nausea prophylaxis. For all individuals with preexisting diabetes, aspirin prophylaxis with 81 mg daily beginning at 12 weeks of gestation is recommended to reduce the risk of preeclampsia.97 Aspirin prophylaxis has not been associated with higher risk for epidural hematoma or peridelivery bleeding, and many patients are maintained on this therapy until the time of delivery. Still, the added risk of aspirin in patients with thrombocytopenia should be considered when determining safety for neuraxial techniques.98

in prophylaxis has not been associated with higher risk for epidural hematoma or peridelivery bleeding, and many patients are maintained on this therapy until the time of delivery. Still, the added risk of aspirin in patients with thrombocytopenia should be considered when determining safety for neuraxial techniques.98 Anesthesiologists should be aware of glucose status of their patients before placing neuraxial anesthesia. General anesthesia is more likely than neuraxial anesthesia to be associated with hyperglycemia during cesarean births.99 Additionally, due to sympathetic blockade of stress response, it is possible that initiation of neuraxial anesthesia could contribute to hypoglycemia in some patients on insulin. Given the pharmacokinetics of insulin clearance and the fact that it may be easier to notice neurologic symptoms of hypoglycemia in awake patients receiving a neuraxial anesthetic, we recommend that blood glucose levels be checked every half hour in patients receiving general anesthesia and every hour for patients receiving neuraxial anesthesia. For patients with T1DM, who need a constant source of insulin, it may be necessary to administer dextrose-containing fluids such as dextrose 5% in lactated Ringer’s solution to prevent hypoglycemia after initiation of a neuraxial anesthetic. This is in alignment with ACOG recommendations.6

Pregnant patients with T2DM and GDM,A2 who are eating during their hospitalization are typically monitored in the same fashion as before hospitalization: a morning fasting fingerstick glucose level is obtained before eating, and then postprandial glucose levels are subsequently checked at 1 or 2 h after meals. Patients who have been instructed to have nothing by mouth (non per os [NPO]) typically have glucose levels checked every 4 h. Just as there has been a significant increase in the utilization of CGM devices during pregnancy for outpatients, there is significant interest and exploration in the use of CGM devices during inpatient management of labor. Although CGM devices are not approved by the U.S. Food and Drug Administration (Silver Spring, Maryland) for inpatient use,62 a number of institutions have developed protocols for their use, and there is at least one study evaluating the use of CGM devices on management of glucose in labor.63 Anesthesiologists should maintain a basic understanding of the functionality of CGM devices, as many pregnant individuals are likely to present for anesthetic care with the devices still in situ, and the presence of a CGM device may impact patient positioning, draping, and use of warming devices.

There are no rigorous data to inform guidelines or practice patterns regarding insulin management on the morning of scheduled births. For individuals planning a scheduled cesarean birth or other surgery, insulin dosing is typically reduced before the procedure due to standard NPO policies.6 We suggest that for patients taking multiple daily injections of insulin, basal dosing be reduced by 25 to 50% depending on the type of insulin. For those patients using wearable insulin pumps to administer insulin, we recommend decreasing the basal rate by 25% preoperatively on the morning of surgery and to further decrease it during the postpartum period. Table 4 includes a summary of recommended adjustments to basal insulin regimens before scheduled surgeries in pregnancy. Adjustment to Basal Insulin Dosing for Patients Made NPO in Anticipation of a Scheduled Anesthetic Note that the insulin dosing adjustments demonstrated in this table will typically not be made by anesthesiologists, and this table should not be used to determine intravenous insulin infusion dosing during labor. Basal insulin dosing should be moderately reduced for patients made NPO before surgery, but not discontinued completely. NPH, Neutral Protamine Hagedorn; NPO, non per os.

medications. In such cases, it may be preferable to transition to an IV insulin infusion. It is important to remember that patients with T1DM need insulin for survival, and that if a wearable pump is to be removed or discontinued in labor, there should be no gap in insulin coverage before initiation of the IV infusion. Usually insulin is discontinued after delivery in patients with GDM, as delivery of the placenta markedly decreases insulin demands. Enteral intake (if not contraindicated) or the use of dextrose-containing maintenance fluids can reduce the risk of maternal hypoglycemia in this period if necessary. For patients with T1DM who do not use a wearable insulin pump, or for patients with poorly controlled T2DM that preceded pregnancy, basal/bolus subcutaneous insulin is typically restarted after birth at markedly reduced levels (approximately 20% of prebirth levels or 50% of prepregnancy levels, respectively). This will help reduce the risk of hypoglycemia due to the metabolic demands of lactation.

As noted earlier, some stand-alone CGM devices can be paired with an insulin pump; combination systems consisting of both a CGM device and an insulin pump are commercially available. Some of the pumps that can be linked to a CGM device include an automatic mode or a suspend-before-low mode that automatically adjusts or suspends insulin delivery based on CGM device readings to help avoid hypoglycemia. All wearable insulin pumps consist of a reservoir of rapid-acting insulin (e.g., lispro or aspart) that typically contains enough insulin to last 2 or 3 days, and a thin cannula that is inserted into subcutaneous tissue of the upper arm, abdomen, hip, buttock, or thigh via a spring-retractable needle for delivery of the insulin. The drug reservoir and delivery tubing are separate components in most pump designs: the drug reservoir is housed in a metal-and-plastic battery-powered device about the size of a deck of cards that can be kept in a pocket or clipped to a belt or bra or other piece of clothing. Such pumps typically have a display screen and electronic controls for operation of the pump, and a flexible plastic tube several inches long that delivers insulin from the pump reservoir to the subcutaneous cannula, which is in turn held in place by a small adhesive patch.

Normal fasting glucose in pregnancy is typically lower than in nonpregnant individuals. Thus, we recommend treating hypoglycemia only when blood glucose less than or equal to 70 mg/dl or patients exhibit symptoms of hypoglycemia.82 For individuals who are able to drink, oral glucose (as from 4 oz of apple juice or other clear liquid carbohydrate beverage) is the preferred treatment. A memorable mnemonic is “the 15-15 rule,” meaning that about 15 g of carbohydrates (the approximate content of 4 oz apple juice) should be administered to treat hypoglycemia, and the blood glucose should be rechecked in 15 min. If the blood glucose is still less than 70 mg/dl, administer another 15 g of carbohydrates until the blood glucose returns to greater than 70 mg/dl on two consecutive checks. For individuals unable to eat, a 50% dextrose injection may be provided: 25 ml D50 (or half a standard premade bag) provides 12.5 g carbohydrate. For individuals without IV access, who cannot swallow, and with glucose less than 50 mg/dl, glucagon 1 mg (1 ml) can be administered intramuscularly or subcutaneously. If there are ongoing risk factors for hypoglycemia, consider use of maintenance fluids containing 5 to 10% dextrose.

Table 6 summarizes considerations for anesthetic and insulin management of patients with diabetes undergoing cesarean birth and receiving either neuraxial or general anesthesia. There is no evidence that either modality should be favored over the other in patients with diabetes—even those who are acutely hyperglycemic—so the same considerations that anesthesiologists use to decide on type of anesthesia for nondiabetic parturients (e.g., urgency of the procedure, coagulation status) are applicable to patients with diabetes. That said, anesthesiologists should remember that the typical comorbidities of diabetes can be present during pregnancy: even young individuals with longstanding poorly controlled T1DM are at an increased risk of renal dysfunction and hypertension (often due to diabetic nephropathy), autonomic neuropathy, hypothyroidism, and ischemic heart disease, all of which may affect general perioperative anesthesia management or planning. For example, patients with preexisting diabetes-related autonomic neuropathy may be especially prone to hypotension with initiation of general or neuraxial anesthesia and resultant sympathetic blockade.83,84 Long-standing T1DM can be associated with glycosylation of collagen in cervical joints and specifically limited head extension at the atlanto-occipital joint, theoretically contributing to difficulties with laryngoscopy, although this concern has not actually been demonstrated in studies.85,86 Considerations for Anesthetic and Insulin Management of Patients with Diabetes Undergoing Cesarean Birth under Neuraxial or General Anesthesia

Table 6 summarizes considerations for anesthetic and insulin management of patients with diabetes undergoing cesarean birth and receiving either neuraxial or general anesthesia. There is no evidence that either modality should be favored over the other in patients with diabetes—even those who are acutely hyperglycemic—so the same considerations that anesthesiologists use to decide on type of anesthesia for nondiabetic parturients (e.g., urgency of the procedure, coagulation status) are applicable to patients with diabetes. That said, anesthesiologists should remember that the typical comorbidities of diabetes can be present during pregnancy: even young individuals with longstanding poorly controlled T1DM are at an increased risk of renal dysfunction and hypertension (often due to diabetic nephropathy), autonomic neuropathy, hypothyroidism, and ischemic heart disease, all of which may affect general perioperative anesthesia management or planning. For example, patients with preexisting diabetes-related autonomic neuropathy may be especially prone to hypotension with initiation of general or neuraxial anesthesia and resultant sympathetic blockade.83,84 Long-standing T1DM can be associated with glycosylation of collagen in cervical joints and specifically limited head extension at the atlanto-occipital joint, theoretically contributing to difficulties with laryngoscopy, although this concern has not actually been demonstrated in studies.85,86 Considerations for Anesthetic and Insulin Management of Patients with Diabetes Undergoing Cesarean Birth under Neuraxial or General Anesthesia GDM, gestational diabetes mellitus; IV, intravenous; T1DM, type 1 diabetes mellitus; T2DM, type 2 diabetes mellitus.

Table 6 summarizes considerations for anesthetic and insulin management of patients with diabetes undergoing cesarean birth and receiving either neuraxial or general anesthesia. There is no evidence that either modality should be favored over the other in patients with diabetes—even those who are acutely hyperglycemic—so the same considerations that anesthesiologists use to decide on type of anesthesia for nondiabetic parturients (e.g., urgency of the procedure, coagulation status) are applicable to patients with diabetes. That said, anesthesiologists should remember that the typical comorbidities of diabetes can be present during pregnancy: even young individuals with longstanding poorly controlled T1DM are at an increased risk of renal dysfunction and hypertension (often due to diabetic nephropathy), autonomic neuropathy, hypothyroidism, and ischemic heart disease, all of which may affect general perioperative anesthesia management or planning. For example, patients with preexisting diabetes-related autonomic neuropathy may be especially prone to hypotension with initiation of general or neuraxial anesthesia and resultant sympathetic blockade.83,84 Long-standing T1DM can be associated with glycosylation of collagen in cervical joints and specifically limited head extension at the atlanto-occipital joint, theoretically contributing to difficulties with laryngoscopy, although this concern has not actually been demonstrated in studies.85,86 Considerations for Anesthetic and Insulin Management of Patients with Diabetes Undergoing Cesarean Birth under Neuraxial or General Anesthesia GDM, gestational diabetes mellitus; IV, intravenous; T1DM, type 1 diabetes mellitus; T2DM, type 2 diabetes mellitus. We recommend that patients receiving IV insulin during labor have two venous access catheters in place—one for fluid administration, and a second dedicated carrier line for insulin and other high-risk infusions. Note that because patients with diabetes are at increased risk for complications such as preeclampsia, it is not uncommon for such patients to require multiple high-risk infusions: for example, oxytocin for induction of labor, magnesium for preeclampsia, dextrose and insulin for glycemic management, and a pressor after initiation of a neuraxial anesthetic. These infusions are at risk of inadvertent bolus during changes in phase of care—such as emergent transfer to an operating room for a stat cesarean birth—and we agree with the unofficial advice from members of the Society for Obstetric Anesthesia and Perinatology (Lexington, Kentucky) Patient Safety Committee, who recommended that insulin and other infusions in labor be given via a three-way connector through dedicated, color-coded tubing without stopcocks or side-injection ports, and should be temporarily discontinued before transport to the operating room.87

DKA is an acute metabolic crisis that occurs due to the relative insufficiency of insulin, not due to hyperglycemia, per se.100–102 The lack of adequate insulin-induced glucose uptake at end-organs results in (1) release of free fatty acids from adipose tissue, which are then oxidized to ketone bodies that bind sodium and potassium, and (2) a perceived hypoglycemia and subsequent release of glucagon stores, worsening any actual hyperglycemia and in turn causing an osmotic diuresis that leads to hypovolemia and further electrolyte depletion. As many as 5 to 10% of pregnant patients with preexisting diabetes may have their pregnancy complicated by DKA.6 The incidence of DKA among patients with diabetes who are pregnant is reported to be much higher than among females with diabetes who are not pregnant.101 While most cases occur in individuals with preexisting T1DM, around 15% of cases present in individuals with T2DM or GDM in modern series.103–105 Most cases of DKA are observed in the third trimester of pregnancy, and while maternal mortality associated with DKA is rare, recent studies have shown a fetal mortality rate of ranging from 6 to 16%.103–105 Thus, it is crucial to maintain a high index of suspicion in order to promptly recognize and manage DKA to improve both maternal and neonatal outcomes.

hird trimester of pregnancy, and while maternal mortality associated with DKA is rare, recent studies have shown a fetal mortality rate of ranging from 6 to 16%.103–105 Thus, it is crucial to maintain a high index of suspicion in order to promptly recognize and manage DKA to improve both maternal and neonatal outcomes. Recently published data suggest that DKA may be underrecognized in pregnancy.106 This may be in part because symptoms of DKA (such as nausea, vomiting, and abdominal pain) overlap significantly with complaints typical of otherwise normal pregnancies, and perhaps in part because DKA in pregnancy frequently presents with euglycemia and sometimes with near-normal laboratory findings such as pH and potassium levels.107 Reported rates of euglycemia in DKA during pregnancy range from 5 to 50% depending on the population.103,105,107 Euglycemia may be common in DKA during pregnancy (1) because the mother is predisposed to an accelerated starvation ketosis characterized by a decrease in glycogenolysis and hepatic glucose production, (2) because of a switch from use of hepatic glycogen to lipolysis and ketone production during fasting, (3) because of increased glucose uptake by the feto-placental unit, (4) because of a physiologic hemodilution of blood glucose, and (5) because of an increased glomerular filtration rate with increased renal glucose excretion.108

f a switch from use of hepatic glycogen to lipolysis and ketone production during fasting, (3) because of increased glucose uptake by the feto-placental unit, (4) because of a physiologic hemodilution of blood glucose, and (5) because of an increased glomerular filtration rate with increased renal glucose excretion.108 Other physiologic changes in pregnancy may also contribute to the difficulties in recognizing DKA, even if capillary glucose values are elevated.101 For instance, an increase in tidal volume and resting minute ventilation are typical of normal pregnancy. This causes hypocarbia and a respiratory alkalosis, which is compensated for by a normal decrease in serum bicarbonate levels to 18 to 21 mM in uncomplicated pregnancies. Serum pH is typically between 7.4 and 7.46 during normal pregnancy, despite this compensatory metabolic acidosis. Blood pH is lowered in DKA as excessive ketone bodies consume bicarbonate buffer, but pH may initially not be lowered to the degree otherwise expected by the high anion gap, or to the degree that would be seen in nonpregnant individuals. As a result, pregnant patients in early DKA may present with only a low normal pH, despite a high anion gap, before rapidly developing a profound metabolic acidosis.101

pH may initially not be lowered to the degree otherwise expected by the high anion gap, or to the degree that would be seen in nonpregnant individuals. As a result, pregnant patients in early DKA may present with only a low normal pH, despite a high anion gap, before rapidly developing a profound metabolic acidosis.101 Clinical presentation of DKA in pregnant patients is similar to the clinical presentation in nonpregnant patients except that the complication of ketosis tends to develop more rapidly.108 Symptoms of DKA in pregnancy include nausea, vomiting, polyuria, polydipsia, dehydration, and change in mental status. Given that more than 70% of pregnancies are complicated by nausea and vomiting,109 underlying DKA could potentially be missed if not suspected. Key laboratory findings sufficient for diagnosis of DKA in pregnancy include evidence of both ketosis and an anion gap acidosis.110 An anion gap greater than 12 mEq/l and positive ketones are sufficient to confirm the diagnosis, regardless of blood sugar. A serum bicarbonate level less than 15 supports the diagnosis, as well as an arterial pH less than 7.3. However, obtaining an arterial sample can be challenging in an obstetrics unit and is not always necessary.

eater than 12 mEq/l and positive ketones are sufficient to confirm the diagnosis, regardless of blood sugar. A serum bicarbonate level less than 15 supports the diagnosis, as well as an arterial pH less than 7.3. However, obtaining an arterial sample can be challenging in an obstetrics unit and is not always necessary. Treatment of DKA in pregnancy is similar to that in nonpregnancy and consists of aggressive fluid replacement, insulin administration, and electrolyte replacement.6,110 Table 7 summarizes the diagnosis and treatment of DKA in pregnancy. Insulin dosing is typically higher in pregnancy than for nonpregnant patients due to a desire to resolve the metabolic disturbances more quickly and thereby reduce the risk of adverse fetal outcomes.100,101 Close monitoring and frequent assessment of laboratory values are essential, with expert opinion suggesting hourly glucose and ketone assessments, and serum electrolytes, blood urea nitrogen, and creatinine checked every 2 h until stable.100,111 Management of Diabetic Ketoacidosis in Pregnancy

Treatment of DKA in pregnancy is similar to that in nonpregnancy and consists of aggressive fluid replacement, insulin administration, and electrolyte replacement.6,110 Table 7 summarizes the diagnosis and treatment of DKA in pregnancy. Insulin dosing is typically higher in pregnancy than for nonpregnant patients due to a desire to resolve the metabolic disturbances more quickly and thereby reduce the risk of adverse fetal outcomes.100,101 Close monitoring and frequent assessment of laboratory values are essential, with expert opinion suggesting hourly glucose and ketone assessments, and serum electrolytes, blood urea nitrogen, and creatinine checked every 2 h until stable.100,111 Management of Diabetic Ketoacidosis in Pregnancy Pregnant patients with DKA should be presumed to be hypovolemic with a fluid deficit around 100 ml/kg actual body weight, or between 6 and 10 l for many pregnant patients. This volume should be replaced within the first 24 to 36 h.100,111 The initial resuscitation fluid of choice for DKA in pregnancy is typically 0.9% normal saline, as pregnancy is often associated with a physiologic 4- to 5-mEq/l decrease in serum sodium due to pregnancy-induced vasodilation and activation of the renin-angiotensin system, and oxytocin activation of renal antidiuretic hormone receptors, among other reasons.112 That said, some recent studies in nonpregnant patients have suggested that balanced crystalloids such as lactated Ringer’s solution or PlasmaLyte (Baxter International, USA) may result in faster DKA resolution, faster insulin discontinuation, lower rates of hypokalemia, and faster normalization of pH with less hyperchloremia.113 The initial recommended rate of fluid resuscitation is the same for pregnant patients as for nonpregnant individuals: an initial slow bolus of 1 to 2 l/h fluid during 1 to 2 h followed by a maintenance infusion at a rate of 150 to 250 ml/h. If or when serum glucose level is less than 200 mg/dl, 5% dextrose should be added to the resuscitation fluids to support insulin activity.110

for pregnant patients as for nonpregnant individuals: an initial slow bolus of 1 to 2 l/h fluid during 1 to 2 h followed by a maintenance infusion at a rate of 150 to 250 ml/h. If or when serum glucose level is less than 200 mg/dl, 5% dextrose should be added to the resuscitation fluids to support insulin activity.110 Because pregnant patients so commonly can present with euglycemia, the most common mistake we see is for providers to not initiate insulin therapy quickly enough or at sufficient levels upon recognition of DKA in pregnancy. It is important to realize that insulin must be given to inhibit ongoing synthesis of ketoacids and thereby correct acidosis. If a patient’s serum glucose level is less than 200 mg/dl, an exogenous sugar source should be administered in the form of 5% dextrose added to maintenance fluids (as described above) to avoid hypoglycemia.6,100,111 If the patient is hyperglycemic, a continuous IV infusion of regular insulin is typically started at a rate of 0.1 U · kg–1 · h–1 after an initial bolus of 0.1 U/kg.6,110 The ongoing insulin rate is adjusted based on changes in serum glucose levels. Due to challenges with managing insulin in these individuals, we typically have them remain NPO until the anion gap metabolic acidosis is corrected. We also strongly recommend against allowing patients to continue to use any wearable subcutaneous insulin pumps during treatment of DKA while on an IV insulin infusion.

s. Due to challenges with managing insulin in these individuals, we typically have them remain NPO until the anion gap metabolic acidosis is corrected. We also strongly recommend against allowing patients to continue to use any wearable subcutaneous insulin pumps during treatment of DKA while on an IV insulin infusion. The IV insulin infusion rate and exogenous dextrose infusion should be adjusted to maintain a serum glucose level at 100 to 150 mg/dl. IV insulin should be continued until serum bicarbonate levels have normalized, the anion gap is less than 12, and ketosis is resolved. Once the metabolic ketoacidosis is resolved, then the patient should be transitioned back to basal-bolus subcutaneous insulin or allowed to restart their subcutaneous insulin pump. The insulin infusion should be stopped 1 to 2 h after resuming basal insulin.

ized, the anion gap is less than 12, and ketosis is resolved. Once the metabolic ketoacidosis is resolved, then the patient should be transitioned back to basal-bolus subcutaneous insulin or allowed to restart their subcutaneous insulin pump. The insulin infusion should be stopped 1 to 2 h after resuming basal insulin. Just as with nonpregnant patients, most pregnant patients with DKA present with a total-body potassium deficit due to osmotic diuresis, emesis, and hyperaldosteronism110 even as measured serum potassium may be normal (or elevated) due to transcellular potassium shifts in the context of acidemia. Administration of insulin and correction of acidosis will shift potassium back into the cell, revealing the underlying hypokalemia. Small retrospective studies have suggested a strong link between maternal hypokalemia in DKA and fetal loss,114 so aggressive and early potassium replacement is appropriate in pregnancy-associated DKA. It is typically recommended that supplemental potassium be administered in patients who present with a serum potassium less than 5.3 mEq/l by adding 20 mEq potassium to each liter of IV fluid administered. Current recommendations are to give fluid and potassium before insulin if potassium is less than 3.3 mEq/l to avoid maternal arrhythmias, respiratory compromise, and the risk of fetal loss.6,100,101,111 When serum potassium is less than 3.3 mEq/l, IV potassium chloride should be given at a rate of 20 to 40 mEq/h, likely in an intensive care unit setting to support rapid correction before insulin infusion.

ess than 3.3 mEq/l to avoid maternal arrhythmias, respiratory compromise, and the risk of fetal loss.6,100,101,111 When serum potassium is less than 3.3 mEq/l, IV potassium chloride should be given at a rate of 20 to 40 mEq/h, likely in an intensive care unit setting to support rapid correction before insulin infusion. The routine use of bicarbonate for treatment of the DKA is not recommended.6,100,101 There are few data to support its use, even in profound maternal acidosis such as a pH less than 6.9.110 Bicarbonate administration can exacerbate hypokalemia, cause a paradoxical increase in cerebral acidemia and thus cerebral edema, and decrease tissue oxygen uptake. Further, if bicarbonate levels are corrected too rapidly, fetal partial pressure of carbon dioxide in the blood levels may be elevated, impairing fetal ability to maintain adequate oxygen transfer.47 Finally, management of DKA in pregnancy requires consideration of fetal well-being, and continuous fetal monitoring is recommended during treatment. Due to maternal academia, fetal heart rate monitoring may show minimal variability and late appearing decelerations, which are reversed upon correction of the academia.6 DKA alone is typically not an indication for birth, and rapid correction of the metabolic disturbances is thought to reduce risk of stillbirth.

Treatment of DKA in pregnancy is similar to that in nonpregnancy and consists of aggressive fluid replacement, insulin administration, and electrolyte replacement.6,110 Table 7 summarizes the diagnosis and treatment of DKA in pregnancy. Insulin dosing is typically higher in pregnancy than for nonpregnant patients due to a desire to resolve the metabolic disturbances more quickly and thereby reduce the risk of adverse fetal outcomes.100,101 Close monitoring and frequent assessment of laboratory values are essential, with expert opinion suggesting hourly glucose and ketone assessments, and serum electrolytes, blood urea nitrogen, and creatinine checked every 2 h until stable.100,111 Management of Diabetic Ketoacidosis in Pregnancy

The incidence of diabetes in pregnancy is increasing. Anesthesiologists should be prepared to manage peripartum insulin therapy, especially during cesarean births. Glucose targets in pregnancy are lower than in other perioperative settings. Continuous glucose monitors, and to a lesser degree wearable insulin pumps, are also increasingly being used in pregnancy, and anesthesiologists should have a basic understanding of their functionality and be prepared for patients who wish to leave their continuous glucose monitors in situ during labor and cesarean births. It is almost always appropriate to use IV insulin infusions to manage hyperglycemia during labor, and except for patients with type 1 and occasionally type 2 diabetes, it is almost always appropriate to discontinue the IV insulin infusion at the time of delivery of the placenta. Anesthesiologists should be aware that the complication of DKA in pregnancy can frequently present with euglycemia and that inpatient interventions such as betamethasone or dexamethasone administration to induce fetal lung maturity can trigger ketoacidosis. Additional research is needed to further refine therapeutic glucose targets in labor, to determine whether HCLs and continuous glucose monitors can be used safely during labor and potentially included in peripartum and operative care, and to enhance recognition and treatment of DKA in pregnancy. Dr. Wernimont is funded by the National Institutes of Health (Bethesda, Maryland; 1R01HD113553-01A1).

The incidence of diabetes in pregnancy is increasing. Anesthesiologists should be prepared to manage peripartum insulin therapy, especially during cesarean births. Glucose targets in pregnancy are lower than in other perioperative settings. Continuous glucose monitors, and to a lesser degree wearable insulin pumps, are also increasingly being used in pregnancy, and anesthesiologists should have a basic understanding of their functionality and be prepared for patients who wish to leave their continuous glucose monitors in situ during labor and cesarean births. It is almost always appropriate to use IV insulin infusions to manage hyperglycemia during labor, and except for patients with type 1 and occasionally type 2 diabetes, it is almost always appropriate to discontinue the IV insulin infusion at the time of delivery of the placenta. Anesthesiologists should be aware that the complication of DKA in pregnancy can frequently present with euglycemia and that inpatient interventions such as betamethasone or dexamethasone administration to induce fetal lung maturity can trigger ketoacidosis. Additional research is needed to further refine therapeutic glucose targets in labor, to determine whether HCLs and continuous glucose monitors can be used safely during labor and potentially included in peripartum and operative care, and to enhance recognition and treatment of DKA in pregnancy. Dr. Wernimont is funded by the National Institutes of Health (Bethesda, Maryland; 1R01HD113553-01A1). Dr. Moheet declares having received research funding from the Cystic Fibrosis Foundation (Bethesda, Maryland), an honorarium for moderation of an education program from Sanofi-Aventis US LLC (Bridgewater, New Jersey), and an honorarium for participating as faculty in a panel discussion in an educational program from Vertex (Boston, Massachusetts). The other authors declare no competing interests.

Dr. Moheet declares having received research funding from the Cystic Fibrosis Foundation (Bethesda, Maryland), an honorarium for moderation of an education program from Sanofi-Aventis US LLC (Bridgewater, New Jersey), and an honorarium for participating as faculty in a panel discussion in an educational program from Vertex (Boston, Massachusetts). The other authors declare no competing interests.