DPP4 cleaves N-terminal dipeptides of the incretin hormones glucose-dependent insulinotropic peptide (GIP) and glucagon-like peptide-1 (GLP-1), leading to their inactivation and halting their actions to promote insulin secretion from pancreatic beta cells and decreased glucose levels, increasing the risk of T2D [140,141,142]. The gene discussed is GIP; the disease is type 2 diabetes mellitus.