TCF7L2 and type 2 diabetes mellitus: Nevertheless, early studies have shown that genetic variants in at least three genes, namely the peroxisome proliferator-activated receptor-gamma gene (PPARγ) [76], the ATP-sensitive potassium channel Kir6.2 (KCNJ11) [77], and the gene encoding for transcription factor 7-like protein 2 (TCF7L2) [78] are associated with increased risks of developing T2D, especially in specific populations [79].