Definition: Gestational diabetes mellitus (GDM) is defined as diabetes diagnosed during pregnancy, typically between 24–28 weeks gestation, with onset or first recognition during pregnancy (ACOG, 2017). It includes some women with previously unrecognized overt diabetes.
- Diagnosis:
- Screening: Universal screening with a 50-g glucose challenge test (GCT) at 24–28 weeks gestation.
- Diagnosis: If GCT ≥140 mg/dL, confirm with a 100-g, 3-hour oral glucose tolerance test (OGTT). Diagnosis is made if ≥2 values meet or exceed thresholds (fasting ≥92 mg/dL, 1-hour ≥180 mg/dL, 2-hour ≥153 mg/dL, 3-hour ≥140 mg/dL).
- Management:
- First-line: Medical nutrition therapy (MNT) and moderate exercise.
- Pharmacotherapy: If glycemic targets (fasting <95 mg/dL, 1-hour postprandial <140 mg/dL, 2-hour <120 mg/dL) are not met, insulin is preferred. Metformin and glyburide may be considered in some cases (ACOG, 2017).
- Monitoring: Frequent self-monitoring of blood glucose (SMBG), fetal growth, and well-being.
- Postpartum:
- Screening: 75-g OGTT at 6–12 weeks postpartum to assess for persistent diabetes or prediabetes.
- Counseling: Lifestyle modification, contraception (especially for women with overt diabetes), and future pregnancy planning with preconception glycemic control.
Rationale: GDM management aims to minimize maternal and fetal complications, with insulin as the preferred pharmacotherapy due to its well-established safety profile in pregnancy. Postpartum screening is critical to identify women at high risk for type 2 diabetes.