Supplementary Material for: Polymorphisms in <i>KCNQ1</i> Are Associated with Gestational Diabetes in a Korean Population

<i>Background:</i> Recent genome-wide association studies in East Asians have identified polymorphisms in <i>KCNQ1</i> as new type 2 diabetes risk variants. The aim of this study was to investigate whether variants in <i>KCNQ1</i> are associated with development of gestational diabetes mellitus (GDM) and measures of oral glucose tolerance test (OGTT) at the time of diagnosis of GDM. <i>Methods:</i> Three candidate single nucleotide polymorphisms (rs2074196, rs2237892, and rs2237895) were genotyped in 869 Korean GDM women and 632 nondiabetic control subjects. Insulin resistance was estimated by homeostasis model assessment and pancreatic β-cell function by the insulinogenic index at 1 h. <i>Results:</i> rs2074196 and rs2237892 were associated with the risk of GDM (OR 1.17, 95% CI 1.01–1.36, p<i> = </i>0.039; OR 1.24, 95% CI 1.07–1.45, p<i> = </i>0.0049). Furthermore, rs2237892 and rs2237895 were nominally associated with a decreased insulinogenic index at the time of GDM diagnosis (p = 0.025 and p = 0.037), whereas no association was observed with measures of insulin resistance. <i>Conclusions:</i> The single nucleotide polymorphisms in <i>KCNQ1</i> showed a significant association with GDM in the Korean population. Although the mechanism is not yet clear, it could be possible that variants in <i>KCNQ1</i> confer a risk for GDM by altering pancreatic β-cell function.