TCF7L2 and type 2 diabetes mellitus: Considering the fact that polymorphisms in the KCNJ11, HNF1A, IRS1, TCF7L2, CDKAL1, CDKN2B, RPSAP52, GPR45 HHEX, IL18, and RUNX2 genes have been connected to type 2 diabetes mellitus (T2DM) and/or periodontitis by genome-wide association studies there is a strong incentive for further studied on this matter [112].