What is the management for a pregnant woman with overt diabetes or gestational diabetes?

Management of Overt Diabetes and Gestational Diabetes in Pregnancy

For gestational diabetes, begin with lifestyle modification (medical nutrition therapy and exercise), and add insulin if glycemic targets are not met within 1-2 weeks; for overt diabetes (preexisting type 1 or type 2), insulin is the mandatory first-line pharmacologic treatment from the start of pregnancy. 1, 2

Initial Assessment and Glycemic Targets

Blood Glucose Monitoring Goals

All pregnant women with diabetes require frequent self-monitoring with the following targets 1, 3:

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

A1C Targets

• Target A1C of <6% to <7% (42-53 mmol/mol), individualized to avoid hypoglycemia 1
• A1C should be monitored monthly due to altered red blood cell kinetics in pregnancy 1
• Critical caveat: A1C is a secondary measure in pregnancy; self-monitoring of blood glucose is primary because A1C may not capture postprandial hyperglycemia that drives macrosomia 1

Management of Gestational Diabetes Mellitus (GDM)

Step 1: Lifestyle Modification (First-Line for ALL GDM)

Medical Nutrition Therapy 1, 3:

• Refer immediately to a registered dietitian familiar with GDM management 1, 3
• Mandatory minimum daily requirements (not flexible) 3:
  • 175g carbohydrate (never reduce below this—risks fetal growth compromise and maternal ketosis)
  • 71g protein
  • 28g fiber
• Distribute carbohydrates across 3 small-to-moderate meals and 2-4 snacks throughout the day 3
• Include an evening snack to prevent accelerated overnight ketosis 3
• Never prescribe hypocaloric diets <1,200 kcal/day as this causes ketonemia 3

Physical Activity 3:

• Recommend at least 150 minutes of moderate-intensity aerobic exercise weekly 3
• Regular exercise lowers fasting and postprandial glucose 3

Expected Success Rate: 70-85% of women with GDM can achieve control with lifestyle modification alone 1, 3

Step 2: Pharmacologic Therapy (If Targets Not Met in 1-2 Weeks)

Insulin is the preferred and first-line medication 1:

• Insulin does not cross the placenta to a measurable extent 1
• Use multiple daily injections with basal-bolus regimen or insulin pump 2

Alternative agents (NOT first-line) 1:

• Metformin and glyburide should NOT be used as first-line agents because both cross the placenta 1
• These lack long-term safety data in offspring 1
• If metformin was used for PCOS to induce ovulation, discontinue by end of first trimester 1

Management of Overt Diabetes (Preexisting Type 1 or Type 2)

Preconception Phase (Ideally)

Glycemic Optimization 1:

• Achieve A1C <6.5% (48 mmol/mol) before conception to minimize risk of congenital anomalies 1
• Observational data show increased risk of anencephaly, microcephaly, congenital heart disease, and caudal regression directly proportional to A1C elevations in first 10 weeks 1

Medication Review 1, 2:

• Immediately discontinue teratogenic medications: ACE inhibitors, ARBs, and statins 1, 2
• Prescribe prenatal vitamins with at least 400 mcg folic acid 1

Complication Screening 1, 2:

• Baseline ophthalmology exam in first trimester, then monitor every trimester based on retinopathy severity 1
• Screen for nephropathy with creatinine and urine albumin-to-creatinine ratio 1

During Pregnancy

Insulin Management 2:

• Insulin is the mandatory first-line pharmacologic agent for type 1 and type 2 diabetes in pregnancy 2
• Expect insulin requirements to double by third trimester, with linear increases of approximately 5% per week starting around 16 weeks gestation 2
• Use multiple daily injections with basal-bolus regimen or insulin pump technology 2

Weight Gain Targets 2:

• Overweight women: 15-25 lb (6.8-11.3 kg)
• Obese women: 10-20 lb (4.5-9.1 kg)
• Never recommend weight loss during pregnancy—increases risk of small-for-gestational-age infants 2

Preeclampsia Prevention 2:

• Prescribe low-dose aspirin 100-150 mg daily starting at 12-16 weeks gestation to reduce preeclampsia risk 2

Hypoglycemia Management 2:

• Educate patients and family on hypoglycemia prevention, recognition, and treatment 2
• Counter-regulatory responses are altered in pregnancy, increasing hypoglycemia risk 2

Advanced Monitoring Options

Continuous Glucose Monitoring (CGM) 1:

• For type 1 diabetes, CGM improves A1C without increasing hypoglycemia and reduces large-for-gestational-age births, neonatal hypoglycemia, and length of stay 1
• Target ranges for CGM in type 1 diabetes 1:
  • Time in range (63-140 mg/dL): goal >70%
  • Time below range (<63 mg/dL): goal <4%
  • Time below range (<54 mg/dL): goal <1%
• No data support CGM use in type 2 diabetes or GDM 1

Postpartum Management

Immediate Postpartum (Overt Diabetes) 2:

• Reduce insulin to 50% of end-pregnancy doses or 80% of pre-pregnancy doses after delivery 2
• Monitor closely for hypoglycemia, especially during breastfeeding 2

Postpartum Screening (GDM) 4:

• Screen for persistent diabetes or prediabetes at 4-12 weeks postpartum with 75g OGTT 4
• Schedule ongoing evaluation every 1-3 years for diabetes screening 4
• Recommend continued lifestyle modifications and breastfeeding to reduce future diabetes risk 4

Critical Pitfalls to Avoid

• Never reduce carbohydrates below 175g/day in GDM—this risks fetal growth compromise and maternal ketosis 3
• Never use metformin or glyburide as first-line agents—insulin is preferred 1
• Never mix insulin detemir (Levemir) with other insulin preparations—profiles of action may change 5
• Never prescribe weight loss during pregnancy—increases risk of small-for-gestational-age infants 2
• Never delay insulin initiation in overt diabetes—it is the mandatory first-line treatment 2
• Monitor for ketonuria if inadequate intake is suspected 3