TCF7L2 and type 2 diabetes mellitus: Among them, several loci, including TCF7L2, CDKAL1, HHEX, SLC30A8, KCNJ11, CDKN2A/B, IGF2BP2, GCKR, IRS1, and CDC123/CAMK1D, have been shown to be associated with type 2 diabetes in different ethnic groups [4],[16]–[21].