TCF7L2 and type 2 diabetes mellitus: The meta-analysis revealed a significant association of the T allele of rs7903146 (IVS3C/T) in TCF7L2 and T2DM (OR 1.23, 95% CI 1.13 to 1.33, p<0.001) but not the C allele of rs290487 (IVS3C/T) (0.99, 0.85–1.15; p  = 0.890).