HOMA-IR as a risk factor of gestational diabetes mellitus and a novel simple surrogate index in early pregnancy

Objective To assess the association between insulin resistance and gestational diabetes mellitus (GDM) in early pregnancy and find a simple surrogate index of the homeostasis model assessment of insulin resistance (HOMA-IR). Methods A total of 700 pregnant women were included in this prospective, double-center, observational cohort study. The glucose and lipid metabolic characterization was performed at 6-12 weeks of pregnancy. All participants underwent a 75-g oral glucose tolerance test at 24-28 weeks of pregnancy. Linear regression analysis was applied to find a novel surrogate index of HOMA-IR. Binary logistic analysis was applied to estimate possible associations of different indices with GDM and insulin resistance. Results GDM was diagnosed in 145 of 700 women with singleton pregnancies (20.7%). HOMA-IR was higher in the GDM group than in the normal glucose tolerance (NGT) group and was an individual risk factor for GDM (adjusted risk ratio RR 1.371, 95% confidence interval [CI] 1.129-1.665, P < 0.001). TyHGB index as the surrogate index of HOMA-IR was represented as TG/HDL-C + 0.7*FBG (mmol/L) +0.1*preBMI (kg/m(2))(where TG/HDL-C is triglyceride/high-density lipoprotein cholesterol; FBG is fasting blood glucose, and preBMI is the pre-pregnancy body mass index [calculated as weight in kilograms divided by the square of height in meters]). The cut-off point of the TyHGB index was 6.0 (area under the curve 0.827, 95% CI 0.794-0.861, P < 0.001) for mild insulin resistance. Conclusion Increased HOMA-IR in early pregnancy was a risk factor of GDM. TyHGB index could be a surrogate index of HOMA-IR and had a predictive value for GDM.