TCF7L2 and type 2 diabetes mellitus: The relationship between Wnt signalling pathways and T2DM was firstly documented by Grant et al in 2006; they found genetic polymorphism of TCF7L2 gene, which encodes an important transcription factor TCF4 in Wnt signalling pathways, contributed to the risk of T2DM through regulation of the expression of proglucagon gene.15