The transcription factor-7 like 2 gene (TCF7L2) was the first locus to be associated with T2D in genome-wide association studies (GWAS) and has been consistently associated with T2D [3, 4], TCF7L2 (previously known as TCF4) encodes a transcription factor that is an effector of the Wnt signaling pathway [5]. This evidence concerns the gene TCF7L2 and type 2 diabetes mellitus.