Resistance to the biological actions of GIP is a hallmark of type 2 diabetesmellitus, with the GIP-mediated incretin effect being severely diminished inpeople with diabetes (Figure2).34 However, despite the well-known importance of the incretin effect toregulate normal blood glucose levels,35 established treatments for type 2 diabetes fail to address this issue.Indeed, incretin-based therapeutics focus largely on augmenting the biologicalactions of the sister incretin glucagon-like peptide-1 (GLP-1). This evidence concerns the gene GIP and diabetes mellitus.