In conclusion, our findings suggest that the genotypes of rs7903146 (IVS3C/T) in TCF7L2 have no major impact on T2DM; however, the CC genotype and the recessive model of rs290487 (IVS3C/T) and the haplotype CC of rs7903146 (IVS3C/T) and rs290487 (IVS3C/T) in TCF7L2 gene are associated with T2DM. The gene discussed is TCF7L2; the disease is type 2 diabetes mellitus.