Similarly, some studies suggest an essential and beneficial role ofTCF7L2 in pancreatic β cell development [28,29], while other studies revealed a destructive role of TCF7L2 byover-expression of TCF7L2 mRNA due to alternatively spliced variants, whichincreased the risk of developing T2D [30]. This evidence concerns the gene TCF7L2 and type 2 diabetes mellitus.