At what gestational age is the routine screening for gestational diabetes mellitus typically performed in most Indian obstetric centers?

Explanation

## Timing of GDM Screening in Pregnancy **Key Point:** Routine universal screening for gestational diabetes is performed between **24–28 weeks of gestation** in most Indian and international guidelines. ### Rationale for 24–28 Week Screening 1. **Physiologic Basis** - Insulin resistance peaks in the second and third trimesters - Placental lactogen and cortisol levels are sufficiently elevated to unmask maternal glucose intolerance - Allows adequate time for intervention before delivery 2. **Clinical Outcomes** - Early detection (24–28 weeks) enables timely lifestyle modification and medication initiation - Reduces risk of macrosomia, polyhydramnios, and preeclampsia - Allows fetal monitoring and appropriate delivery planning **High-Yield:** This is the **standard recommendation** across ICOG (Indian College of Obstetricians and Gynaecologists), WHO, and ACOG guidelines. ### Two-Step vs. One-Step Approach | Approach | Screening Test | Timing | Diagnostic Test | | --- | --- | --- | --- | | **Two-step (ACOG)** | 50-g GCT (non-fasting) | 24–28 weeks | 75-g or 100-g OGTT if GCT ≥ 140 mg/dL | | **One-step (WHO)** | 75-g OGTT (fasting) | 24–28 weeks | Diagnostic if any threshold exceeded | **Clinical Pearl:** In India, both approaches are used depending on institutional protocol. The one-step approach (WHO/ICOG) is increasingly preferred as it is simpler and identifies more cases of GDM.