Currently, at least 40 genetic loci have been convincingly associated with T2DM, including KCNQ1, CDKAL1, TCF7L2, HMG20A, HNF4A, HNF1B, and DUSP9. Several findings reported independent genome wide association (GWA) in Caucasians, which did not only confirm the effect of PPARG, KCNJ11 and TCF7L2, but also identified six novel susceptibility loci including CDKAL1, CDKN2A-CDKN2B, IDE-KIF11-HHEX, IGF2BP2, SLC30A8 and FTO [3–6]. The gene discussed is TCF7L2; the disease is type 2 diabetes mellitus.