The first association between the Wnt/β-catenin pathway and metabolic disease came about in 2004, in which some specific SNPs in β-catenin-independent WNT5B increased susceptibility for type 2 diabetes (Kanazawa et al., 2004), initiating the discoveries of WNT10B (Christodoulides et al., 2006) and TCF7L2 (Grant et al., 2006; Tong et al., 2009; Savic et al., 2011; Takamoto et al., 2014). The gene discussed is TCF7L2; the disease is type 2 diabetes mellitus.