In the context of screening for gestational diabetes mellitus (GDM) in India, which of the following is the most common cutoff value used for the oral glucose tolerance test (OGTT) to define GDM in the second trimester?

Explanation

## GDM Screening Cutoff Values in India **Key Point:** The International Association of Diabetes in Pregnancy Study Group (IADPSG) criteria, adopted by most Indian guidelines including ICMR and FOGSI, define GDM using a 75-g OGTT with cutoff values of fasting ≥92 mg/dL and 2-hour ≥153 mg/dL. ### Evolution of GDM Diagnostic Criteria Historically, the Carpenter-Coustan criteria (fasting ≥105 mg/dL, 2-hour ≥165 mg/dL) were widely used, but the IADPSG criteria (2010) lowered thresholds based on the HAPO study, which demonstrated increased maternal and fetal adverse outcomes at lower glucose levels than previously recognized. ### IADPSG Criteria for 75-g OGTT | Time Point | Threshold (mg/dL) | Threshold (mmol/L) | |------------|-------------------|--------------------| | **Fasting** | ≥92 | ≥5.1 | | **1-hour** | ≥180 | ≥10.0 | | **2-hour** | ≥153 | ≥8.5 | **High-Yield:** Only ONE abnormal value is needed to diagnose GDM using IADPSG criteria (not two, as in older Carpenter-Coustan criteria). This single-step approach increases detection rates and is now the standard in India. **Mnemonic:** **IADPSG-75** — 75-g OGTT with fasting ≥92, 1-hour ≥180, 2-hour ≥153 (remember: lower thresholds = higher sensitivity). ### Clinical Implementation in India **Clinical Pearl:** The ICMR guidelines (2018) and FOGSI recommendations endorse IADPSG criteria for universal screening at 24–28 weeks gestation. This has increased GDM detection rates in India from ~5–10% (using older criteria) to 15–20%, reflecting true prevalence and improved identification of at-risk pregnancies. [cite:ICMR GDM Guidelines 2018, FOGSI Guidelines]