Association of MTNR1B polymorphisms with gestational diabetes mellitus and its interaction with pre-pregnancy body mass index in Northern Han Chinese women

To examine the association of MTNR1B gene polymorphisms with the risk of gestational diabetes mellitus (GDM), and further assess whether pre-pregnancy body mass index (BMI) interacted with MTNR1B gene polymorphisms on GDM. This case-control study included 537 GDM cases and 751 controls. Genotyping of the MTNR1B rs1387153, rs10830963, rs4753426, rs3781637 was performed. Pre-pregnancy BMI was classified into three groups: underweight (<18.5 kg/m2), normal weight (18.5-23.9 kg/m2), overweight or obese (BMI ≥24 kg/m2) according to the Chinese standard. Logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) between women with and without GDM. After adjusting for potential confounders, each copy of the MTNR1B rs1387153_T allele was associated with a 34% increased risk of GDM (OR: 1.34, 95% CI: 1.13-1.59, p = 0.001), while each copy of the MTNR1B rs10830963_G allele was associated with a 56% higher risk of GDM (OR: 1.56, 95% CI: 1.31-1.85, p < 0.001). A significant interaction between MTNR1B rs1387153 and pre-pregnancy BMI category on the risk of GDM was identified (P for interaction = 0.016 under an additive model and 0.007 under a dominant model). Compared to carriers of rs1387153_CC genotype with pre-pregnancy normal weight, overweight or obese women who carried the genotype of TT or CT had a 3.15-fold increased risk of GDM (OR = 3.15, 95% CI: 2.16-4.59). This study found that MTNR1B rs1387153_T and rs10830963_G were associated with an increased risk of GDM, and pre-pregnancy BMI might influence the effect of MTNR1B rs1387153 polymorphism on the occurrence of GDM.