Diagnostic accuracy of the triglyceride-glucose index for gestational diabetes screening: evidence from an Indian cohort

Background: Gestational diabetes mellitus (GDM) is associated with significant maternal and fetal complications, yet current screening methods such as the oral glucose tolerance test (OGTT) remain cumbersome, costly and inconvenient. The triglyceride-glucose (TyG) Index is an emerging surrogate marker of insulin resistance and may offer a simpler alternative for GDM screening. To evaluate the diagnostic accuracy of the TyG Index for screening GDM at 24–28 weeks of gestation in an Indian population. Methods: This cross-sectional study included 270 pregnant women (19–40 years) attending antenatal care at Lady Hardinge Medical College, New Delhi (January 2021–August 2022). Women with pre-existing diabetes, hypertension, liver disease or medications affecting glucose or triglycerides were excluded. All participants underwent fasting OGTT using IADPSG criteria and simultaneous fasting triglyceride measurement. The TyG Index was calculated as: TyG=Ln (fasting triglycerides (mg/dl) ×fasting plasma glucose (mg/dl))/2. ROC analysis was conducted to determine the optimal cut off and diagnostic performance metrics were computed. Results: The TyG Index demonstrated a strong discriminative ability with an AUC of 0.874 (95% CI: 0.829–0.912). A cut off value of 4.9 yielded a sensitivity of 82.72%, specificity of 78.31%, PPV of 62.04%, NPV of 91.36% and overall accuracy of 79.63%. Using this threshold, GDM prevalence was overestimated (40%) compared to OGTT-based prevalence (30%). Women with TyG>4.9 had significantly higher Fasting, 1-hour and 2-hour glucose levels (p