GCG and diabetes mellitus: Interestingly, the higher plasma concentrations of incretins [37] and greater protein abundance of GLP-1 receptor in untreated diabetics together with the lower pancreatic insulin transcript abundance suggest that feline diabetes is unlikely to be due to a deficit in incretin secretion as in human diabetes [24,53], but very likely due to impaired incretin receptor signaling to potentiate insulin secretion from the pancreas.