Gestational Diabetes Mellitus Predictors Based on First Trimester Lipid and Glucose- Derived Indices: A Single Center Retrospective Cohort Study

Background: Gestational diabetes mellitus (GDM) is associated with substantial maternal and neonatal morbidity. Early identification of women at risk remains a clinical priority. This study aimed to evaluate whether simple indices derived from first-trimester fasting triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and glucose—namely the triglyceride-glucose (TyG) index, TG/HDL-C ratio, and a lipid-based composite insulin resistance surrogate (Lipid-IR)—predict subsequent development of GDM. Methods: This single-center retrospective cohort included 679 pregnant women with first-trimester fasting lipid and glucose measurements. Of these, 342 developed GDM (diagnosed at 24–28 weeks using a two-step approach and Carpenter–Coustan criteria), and 337 remained normoglycemic. Baseline demographic, anthropometric, laboratory, and obstetric/neonatal variables were compared. TyG was calculated as ln[(TG (mg/dL) × fasting glucose (mg/dL))/2], TG/HDL-C as TG divided by HDL-C (mg/dL), and Lipid-IR as ln(2×TG (mg/dL) + total cholesterol (mg/dL)). Independent predictors were identified through multivariable logistic regression. Receiver operating characteristic (ROC) analysis evaluated discriminative ability and optimal cut-off points using Youden’s J statistic. Results: Compared with controls, women who developed GDM were older and had higher pre-pregnancy and current body weights, body mass index (BMI), and waist circumference (all p ≤ 0.003). They also exhibited higher fasting glucose, HbA1c, insulin, TG, total cholesterol, and liver enzyme levels, and lower HDL-C concentrations (all p ≤ 0.03). Cesarean delivery was more frequent among women with GDM (58% vs. 32%; p = 0.001), with higher birth weights and lower 5-minute Apgar scores. In multivariable models, TyG (OR 3.10), Lipid-IR (OR 1.85), and TG/HDL-C (OR 2.12) were independently associated with GDM (all p < 0.001). Discrimination was strong, with AUCs of 0.88 for TyG, 0.82 for Lipid-IR, and 0.79 for TG/HDL-C; combining all three indices increased the AUC to 0.92 (sensitivity 89%, specificity 85%). Conclusion: First-trimester lipid–glucose indices, particularly the TyG index, show robust predictive performance for GDM and may enable early risk stratification and preventive interventions before oral glucose tolerance testing. Trial registration: Not applicable (observational, non-interventional study).