INS and type 2 diabetes mellitus: Several GWAS have identified variants positioned in the GIPR locus, including the E354Q GIPR variant, to associate with increased 2-h glucose levels, decreased insulin secretion, insulin resistance and risk of T2D (Almind et al., 1998; Hu et al., 2010; Sauber et al., 2010; Saxena et al., 2010), further supporting the importance of the GIP-GIPR axis in glucose regulation.