Recent GWAS have identified a large number of T2D susceptibility loci (Scott et al., 2017; Mahajan et al., 2014; Wellcome Trust Case Control Consortium et al., 2012; Voight et al., 2010), the majority of which affect insulin secretion and beta cell function (Dimas et al., 2014; Wood et al., 2017). Here, INS is linked to type 2 diabetes mellitus.