KCNQ1 and type 2 diabetes mellitus: Studies were selected according to the following inclusion criteria: full text could be found; the case–control studies focused on the relevance of KCNQ1 rs2237892 polymorphism and T2DM risk; the KCNQ1 rs2237892 genotype was obtained, and association between the KCNQ1 rs2237892 SNP and T2DM prevalence was assessed.