What is the management of diabetes in pregnancy?

Management of Diabetes in Pregnancy

Women with diabetes in pregnancy require intensive glycemic control with insulin as first-line therapy, targeting fasting glucose <95 mg/dL and 1-hour postprandial <140 mg/dL, with preconception A1C <6.5% to minimize congenital malformations and adverse outcomes. 1

Preconception Care and Planning

All women of childbearing age with diabetes must receive preconception counseling emphasizing the critical importance of achieving optimal glycemic control before conception. 2, 1

Glycemic Targets Before Conception

• Target A1C <6.5% before conception to achieve the lowest risk of congenital anomalies (anencephaly, microcephaly, congenital heart disease, renal anomalies, caudal regression), preeclampsia, and preterm birth 2, 1, 3
• Organogenesis occurs at 5-8 weeks gestation, often before women know they are pregnant, making preconception optimization essential 2, 1
• Effective contraception must be prescribed and used until glycemic targets are achieved 1, 3

Medication Review and Adjustments

• Immediately discontinue teratogenic medications: ACE inhibitors, angiotensin receptor blockers, and statins 2, 1, 3
• Initiate folic acid supplementation at 400 mg daily (some guidelines recommend higher doses for women with diabetes) 2, 3

Comprehensive Screening

• Diabetes-specific testing: A1C, creatinine, urinary albumin-to-creatinine ratio 2, 1
• Thyroid-stimulating hormone testing 2
• Comprehensive ophthalmologic examination for diabetic retinopathy 2, 1, 3
• Standard preconception labs: rubella, rapid plasma reagin, hepatitis B, HIV, Pap smear, blood typing 2

Multidisciplinary Team Approach

• Ideally manage women with preexisting diabetes in a multidisciplinary clinic including endocrinologist, maternal-fetal medicine specialist, registered dietitian nutritionist, and diabetes care and education specialist 2, 3

Glycemic Targets During Pregnancy

The A1C target in pregnancy is <6% if achievable without significant hypoglycemia, with an alternative target of <7% if necessary to prevent hypoglycemia. 2, 1, 3

Self-Monitoring Blood Glucose Targets

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

These targets are stricter than non-pregnant individuals due to increased red blood cell turnover that lowers normal A1C in pregnancy 2

Glucose Monitoring Strategy

• Fasting and postprandial self-monitoring of blood glucose is the primary tool for achieving optimal glucose control 2, 3
• Continuous glucose monitoring (CGM) can be used as an adjunct to self-monitoring but should not replace traditional pre- and postprandial self-monitoring 2, 1, 3
• CGM reduces large-for-gestational-age births, neonatal hypoglycemia, and length of hospital stay specifically in type 1 diabetes 2, 3
• Do not use estimated A1C or glucose management indicator calculations in pregnancy as they are inaccurate 2

Pharmacologic Management

Insulin Therapy (First-Line)

Insulin is the preferred first-line medication for managing both preexisting and gestational diabetes during pregnancy because it does not cross the placenta to a measurable extent. 1, 3, 4

• Use physiologic basal-bolus regimens with rapid-acting insulin for meals and long-acting insulin for basal coverage 3
• Either multiple daily injections or insulin pump technology can be used in type 1 diabetes 1
• Insulin requirements increase progressively with each trimester due to increasing insulin resistance from placental hormones 5
• Insulin requirements decrease dramatically immediately after delivery of the placenta, requiring rapid dose reduction to prevent hypoglycemia 1, 3

Oral Antihyperglycemic Agents

While insulin remains preferred, metformin and glyburide are widely used alternatives 2:

• Metformin: Limited data suggest no clear association with major birth defects or miscarriage, though most oral agents cross the placenta 2, 4
• The FDA label for metformin states that published studies have not reported a clear association with major birth defects or adverse outcomes, but insufficient data exist to definitively establish absence of risk 4
• Most oral agents lack long-term safety data in pregnancy 2

Medical Nutrition Therapy and Lifestyle

Gestational diabetes should be managed first with diet and exercise, with medications added only if glycemic targets are not achieved. 2

• Consistent carbohydrate intake is essential to match insulin dosing and prevent glucose fluctuations 1, 3
• The food plan should provide adequate calories to promote fetal/neonatal and maternal health while achieving glycemic goals and appropriate gestational weight gain 1
• Regular moderate exercise is recommended 1, 3
• Comprehensive nutrition assessment should address overweight/obesity or underweight status, meal planning, correction of dietary deficiencies, caffeine intake, and safe food preparation 2

Monitoring for Complications

Diabetic Retinopathy

• Women with pregestational diabetes require a baseline ophthalmology exam in the first trimester, then monitoring every trimester as indicated by degree of retinopathy 2
• Women with preexisting diabetic retinopathy need close monitoring during pregnancy to assess for progression and provide treatment if indicated 1, 3
• Rapid implementation of euglycemia in the setting of retinopathy is associated with worsening of retinopathy 1

Preeclampsia Prevention

• Women with type 1 or type 2 diabetes should be prescribed low-dose aspirin 60-150 mg/day (typically 81 mg) by the end of the first trimester to lower the risk of preeclampsia 1, 6, 3

Diabetic Ketoacidosis

• Monitor for diabetic ketoacidosis, which can occur at lower blood glucose levels during pregnancy 6

Postpartum Management

Immediate Postpartum Period

• Insulin requirements decrease dramatically after delivery of the placenta, requiring close monitoring and rapid dose reduction to prevent hypoglycemia 1, 3

Screening for Persistent Diabetes

• Women with gestational diabetes should be tested for persistent diabetes or prediabetes at 4-12 weeks postpartum with a 75-g oral glucose tolerance test 1, 6, 3
• Provide lifelong screening for type 2 diabetes or prediabetes every 1-3 years for women with history of gestational diabetes 6

Additional Postpartum Care

• A contraceptive plan should be discussed and implemented with all women with diabetes of reproductive potential 1, 6
• Encourage breastfeeding to reduce the risk of maternal type 2 diabetes 6
• Metformin is present in human milk at low levels (infant doses approximately 0.11-1% of maternal weight-adjusted dosage), though insufficient information exists to determine effects on breastfed infants 4

Common Pitfalls to Avoid

• Do not rely on A1C alone during pregnancy - use self-monitoring blood glucose as the primary tool, as A1C is physiologically lower in pregnancy 2, 3
• Do not continue ACE inhibitors, ARBs, or statins - these are teratogenic and must be stopped before conception 2, 1, 3
• Do not delay insulin initiation in gestational diabetes - if glycemic targets are not achieved with lifestyle modifications within 1-2 weeks, start insulin 3
• Do not forget to adjust insulin doses postpartum - failure to rapidly reduce insulin after delivery can cause severe hypoglycemia 1, 3
• Do not use CGM metrics as a substitute for self-monitoring blood glucose - CGM is an adjunct only 2, 1, 3