TCF7L2 and type 2 diabetes mellitus: The rs12255372, rs7903146, and rs7901695 loci of TCF7L2 were all significantly associated with T2DM under the codominant and log-additive models, with log-additive ORs of 2.06 (95%CI = 1.45–2.93), 1.43 (95%CI = 1.03–1.97), and 2.08 (95%CI = 1.56–2.77), respectively.