We found a significant relationship between KCNQ1 rs2237895 A⟶C gene polymorphism and T2DM risk under the dominant model (OR, 2.33; 95% CI, 1.46–3.70; p − 0.0003) and codominant model (OR, 1.85; 95% CI, 1.16–2.95; p − 0.009), whereas no significant relationship was found under the recessive model (OR, 1.44; 95% CI, 0.76–2.71; p − 0.259). Here, KCNQ1 is linked to type 2 diabetes mellitus.