Management of Gestational Diabetes Mellitus

Gestational diabetes mellitus is glucose intolerance with onset or first recognition during pregnancy, typically diagnosed at 24-28 weeks via 75 g oral glucose tolerance test using IADPSG/ADA thresholds: fasting >=92 mg/dL, 1-hour >=180 mg/dL, or 2-hour >=153 mg/dL. Early screening at first prenatal visit is recommended for high-risk women.

Management begins with medical nutrition therapy (carbohydrate-controlled, 30-35 kcal/kg pregravid weight) and 30 minutes of moderate exercise most days. Self-monitored capillary glucose four times daily targets fasting <95 mg/dL, 1-hour postprandial <140 mg/dL, and 2-hour <120 mg/dL.

Pharmacotherapy is added when 25-30% of values exceed targets within 1-2 weeks. Insulin remains the gold standard (NPH, detemir, aspart, lispro) given its non-placental crossing. Metformin is acceptable alternative with patient counseling about transplacental passage. Antepartum surveillance with weekly NSTs from 32 weeks, fetal growth ultrasound, and timing of delivery at 39-40 weeks for controlled GDM. Postpartum 75 g OGTT at 6-12 weeks identifies persistent type 2 diabetes.