Before and after adjusting for sex, age, anthropometric measurements, biochemical indexes, smoking and alcohol consumption, the AC and CC genotype and the combined AC + CC genotype of KCNQ1 rs151290 were significantly associated with higher risk of T2DM (OR = 1.482, 95% CI = 1.062–2.069; 1.544, 1.097–2.172; 1.509, 1.097–2.077; adjusted OR = 1.539, 95% CI = 1.015–2.332; 1.641, 1.070–2.516; 1.582, 1.061–2.358, respectively; p < 0.05). The gene discussed is KCNQ1; the disease is type 2 diabetes mellitus.