What are the recommended management strategies for pre‑gestational (type 1 or type 2) and gestational diabetes in pregnancy, including pre‑conception counseling, glycemic targets (HbA1c < 6.5 %, fasting glucose < 95 mg/dL, 1‑hour post‑prandial < 140 mg/dL, 2‑hour post‑prandial < 120 mg/dL), insulin therapy, monitoring, delivery timing, and postpartum follow‑up?

Management of Diabetes Mellitus in Pregnancy

All women with diabetes planning pregnancy must achieve HbA1c <6.5% before conception and immediately discontinue ACE inhibitors, ARBs, and statins, as these medications are teratogenic and directly increase the risk of congenital anomalies, fetal renal defects, and fetal death. 1, 2

Preconception Care and Counseling

Glycemic Optimization Before Conception

• Target HbA1c <6.5% before attempting conception, ideally as close to 6% as possible without significant hypoglycemia, as this is the single most important intervention to reduce congenital anomalies, preeclampsia, macrosomia, and perinatal mortality 1, 2
• Prescribe effective contraception immediately and continue until HbA1c targets are achieved, which typically requires 3-6 months of intensive management 2, 3
• Monitor HbA1c monthly during preconception optimization to track progress 2
• Organogenesis occurs at 5-8 weeks gestation when most women don't yet know they're pregnant, making preconception control critical 2

Mandatory Medication Review and Adjustments

Medications to discontinue immediately:

• ACE inhibitors and ARBs must be stopped before conception due to associations with fetal renal anomalies, oligohydramnios, and fetal death 2, 3
• Statins are pregnancy category X and must be discontinued in all sexually active women not using reliable contraception 1, 2

Medications that may be continued:

• Metformin may be continued during preconception and potentially throughout pregnancy, as it does not increase fetal anomalies and may reduce neonatal hypoglycemia 2
• Glyburide is widely used alongside insulin and metformin, though it has higher treatment failure rates than metformin 1, 2

Alternative medications for comorbidities:

• Switch antihypertensives to methyldopa, labetalol, or long-acting nifedipine with target blood pressure 110-135/85 mmHg 2
• Start low-dose aspirin 100-150 mg daily at 12-16 weeks gestation to reduce preeclampsia risk 2

Comprehensive Preconception Testing

Diabetes-specific testing:

• HbA1c, thyroid-stimulating hormone, serum creatinine, and urine albumin-to-creatinine ratio 1, 3
• Dilated eye examination before conception, as pregnancy accelerates diabetic retinopathy progression 1, 3

General preconception testing:

• Rubella, syphilis, hepatitis B, HIV testing, Pap smear, cervical cultures, blood typing 1
• Prescribe prenatal vitamins with at least 400 mcg folic acid (ideally 400-800 mcg) immediately 1, 2, 3

Multidisciplinary Care Coordination

• Refer to a multidisciplinary clinic including endocrinologist, maternal-fetal medicine specialist, registered dietitian nutritionist, and diabetes care educator 1, 2, 3
• This team-based approach has been shown to improve pregnancy outcomes and achieve better glycemic control 1

Glycemic Targets During Pregnancy

Blood Glucose Monitoring Targets

For gestational diabetes and pregestational diabetes, the following capillary glucose targets apply:

• Fasting plasma glucose <95 mg/dL (5.3 mmol/L) 1, 3
• 1-hour postprandial glucose <140 mg/dL (7.8 mmol/L) 1, 3
• 2-hour postprandial glucose <120 mg/dL (6.7 mmol/L) 1, 3

For women with preexisting type 1 or type 2 diabetes:

• Premeal, bedtime, and overnight glucose 60-99 mg/dL (3.3-5.4 mmol/L) 1
• Peak postprandial glucose 100-129 mg/dL (5.4-7.1 mmol/L) 1

HbA1c Targets During Pregnancy

• Ideally target HbA1c <6% (42 mmol/mol) if achievable without significant hypoglycemia 1
• The target may be relaxed to <7% (53 mmol/mol) if necessary to prevent hypoglycemia 1
• HbA1c is lower in normal pregnancy than in nonpregnant women due to increased red blood cell turnover 1
• Monitor HbA1c more frequently during pregnancy (e.g., monthly) due to altered red blood cell kinetics 1

Monitoring Strategy

• Fasting and postprandial self-monitoring of blood glucose is mandatory in both gestational and pregestational diabetes 1
• Women with preexisting diabetes using insulin pumps or basal-bolus therapy should also test preprandially to adjust rapid-acting insulin doses 1
• Continuous glucose monitoring (CGM) can help achieve HbA1c targets when used in addition to self-monitoring 1
• CGM can reduce macrosomia and neonatal hypoglycemia in type 1 diabetes pregnancy when used alongside traditional pre- and postprandial targets 1
• CGM metrics should be used as an adjunct but not as a substitute for self-monitoring of blood glucose 1
• Do not use estimated HbA1c or glucose management indicator calculations in pregnancy 1

Insulin Therapy During Pregnancy

Insulin as Preferred Agent

• Insulin is the preferred medication for managing diabetes in pregnancy due to lack of long-term safety data for noninsulin agents 1
• All insulins are pregnancy category B except glargine and glulisine, which are category C 1

Insulin Dosing Adjustments Throughout Pregnancy

First trimester:

• Enhanced insulin sensitivity leads to lower glucose levels and decreased insulin requirements 1
• Total daily insulin dose often decreases during this period 1

Second and third trimesters:

• Insulin resistance increases exponentially, requiring weekly or biweekly insulin dose increases 1
• Insulin resistance levels off toward the end of the third trimester 1

Insulin distribution:

• A smaller proportion of total daily dose should be given as basal insulin 1
• A greater proportion should be given as prandial insulin to match postprandial hyperglycemia 1

Nutritional Coordination with Insulin

• Women must eat consistent amounts of carbohydrates to match insulin administration and avoid hyperglycemia or hypoglycemia 1
• Referral to a registered dietitian is essential to establish a food plan, insulin-to-carbohydrate ratios, and weight gain goals 1, 2

Management of Gestational Diabetes Mellitus

• GDM should be managed first with diet and exercise, with medications added only if needed 1
• If lifestyle modifications fail to achieve glycemic targets, insulin is the preferred pharmacologic agent 1
• Metformin and glyburide are widely used alternatives, though they cross the placenta and lack long-term safety data 1

Ophthalmologic Monitoring

• Women with pregestational diabetes require a dilated eye examination ideally before pregnancy or in the first trimester 1, 3
• Monitor every trimester during pregnancy based on degree of retinopathy 1
• Continue monitoring for 1 year postpartum as pregnancy increases risk of retinopathy development and progression 1

Delivery Timing Considerations

• Target plasma glucose levels during active labor are 80-110 mg/dL 4
• An insulin drip is recommended to achieve these targets during active labor 4
• Women with poor glycemic control (HbA1c >6.5%) have significantly shorter gestational periods, more preterm labor, and more operative deliveries 5

Postpartum Management

Immediate Postpartum Period

• Insulin doses must be reduced immediately after delivery and glucose closely monitored due to enhanced insulin sensitivity 4
• Insulin requirements drop dramatically after placental delivery 4

Breastfeeding Support

• Breastfeeding is highly recommended due to maternal benefits (increased insulin sensitivity, weight loss) and infant benefits (reduced prevalence of overweight) 4
• Breastfeeding increases insulin sensitivity and may require further insulin dose adjustments 4

Contraception and Follow-up

• Counsel on contraceptive options, including long-acting reversible contraception 6
• Transition care to primary care provider with appropriate diabetes follow-up 7
• Women with gestational diabetes require postpartum glucose testing to screen for persistent diabetes 1

Critical Pitfalls to Avoid

• Never delay medication review until pregnancy is confirmed—teratogenic exposure occurs during organogenesis at 5-8 weeks when women may not know they're pregnant 2
• Do not rely solely on HbA1c during pregnancy, as it represents an average and may not capture physiologically relevant glycemic parameters; self-monitoring of blood glucose is essential 1
• Avoid setting overly aggressive targets that lead to significant hypoglycemia, particularly in women with type 1 diabetes and history of hypoglycemia unawareness 1
• Do not use CGM as a replacement for self-monitoring of blood glucose—it should only be used as an adjunct 1
• Recognize that women with preexisting diabetes have significantly greater risk than those with GDM and require more intensive monitoring 1