DPP4 and type 2 diabetes mellitus: Dipeptidyl peptidase-4 (DPP-4), which has been proposed as a target for pharmacological intervention in patients with type 2 diabetes [18], was primarily found not only in the brush-border membranes of the kidney and the small intestine but also in other tissues (hepatocytes around bile canaliculi, epithelial cells of the pancreas, and in capillary endothelium) and in a soluble form in plasma [19].