KCNQ1, which is located at chromosome 11p15.5 and near a candidate region at 11p13-p12 and mainly encodes a protein for a voltage-gated potassium channel required for the repolarization phase of the cardiac action potential, has been proved to be associated with type 2 diabetes mellitus (T2DM). The gene discussed is KCNQ1; the disease is diabetes mellitus.