Gestational Diabetes Mellitus (GDM)
GDM is defined as carbohydrate intolerance with onset or first recognition during pregnancy. It results from pregnancy-induced insulin resistance mediated by placental hormones (e.g., human placental lactogen).
Screening & Diagnosis
- Timing: Usually screened between 24 and 28 weeks of gestation.
- Two-Step Approach (Common in the US):
- 50g non-fasting glucose challenge test (GCT).
- If abnormal, followed by a 100g 3-hour oral glucose tolerance test (OGTT).
Maternal & Fetal Risks
| Risk Category | Complication |
|---|---|
| Fetal | Macrosomia, shoulder dystocia, neonatal hypoglycemia, polycythemia, hyperbilirubinemia. |
| Maternal | Pre-eclampsia, future risk of developing Type 2 Diabetes Mellitus. |
High-Yield Exam Pearl:
- Management: First-line is Medical Nutrition Therapy (MNT) and exercise. If glycemic targets are not met, Insulin remains the gold standard pharmacological treatment.
- Postpartum: Perform a 2-hour 75g OGTT at 6–12 weeks postpartum to screen for persistent glucose intolerance.