GSTP1 and type 2 diabetes mellitus: The V allele of GSTP1 and C allele of KCNQ1 were both found to be associated with T2DM risk, with the greatest significant risk associated with the V/V genotype under the codominant model for GSTP1 (OR = 3.10, 95%CI = 1.67–5.76) and the C/C genotype under the recessive model for KCNQ1 (OR = 1.67, 95%CI = 1.13–2.47).