Inflammatory markers mediate the association of the Zhejiang University index with gestational diabetes mellitus: data from NHANES 2007–2020

BACKGROUND: Gestational diabetes mellitus (GDM) threatens maternal and infant health, yet early prediction is challenging. The Zhejiang University (ZJU) index, reflecting insulin resistance and hepatic lipid metabolism, predicts metabolic diseases, but its role in GDM across multiethnic populations is unclear. METHODS: This study analyzed NHANES 2007-2020 data from US women aged 20-45. Weighted logistic regression, restricted cubic spline (RCS), subgroup, and ROC analyses assessed ZJU index and GDM. Mediation analysis evaluated inflammatory ratios. Sensitivity analysis excluded women with chronic diseases or medication use. RESULTS: Among 2240 women, 10% had GDM. Higher ZJU index was linearly associated with increased GDM risk; highest quartile had over twice the odds (OR = 2.25, 95% CI: 1.10-3.41). ZJU index outperformed BMI, FPG, ALT, AST (AUC = 0.718). PHR and LHR partially mediated the association. Sensitivity analysis confirmed robustness. CONCLUSION: ZJU index is a strong, independent predictor of GDM, outperforming traditional markers. HDL‑related inflammatory markers partially mediate this association, suggesting immunometabolic pathways. Further studies are needed for validation in broader populations.