Angiotensin II in Type 2 Diabetes Mellitus

Angiotensin II (Ang II) is well-known as a systemic vasoconstrictor but recently a novel role for the peptide in endocrine function has been suggested and it has been linked to the pathophysiology of type 2 diabetes mellitus. According to several large-scale clinical studies, blocking Ang II prevented the onset of type 2 diabetes in potential patients. Type 2 diabetes is a complicated disease that is primarily characterized by insulin resistance and relative insulin deficiency mediated by numerous organs. Among these organs, the pancreas, adipose tissue, skeletal muscle and liver are the most prominent in maintaining glucose homeostasis. Interestingly, locally generated Ang II has been identified in these organs, where it plays different physiological roles and is produced in relatively high amounts with significant function. In type 2 diabetic human patients or animal models, Ang II, its generating enzymes and receptors are upregulated and trigger detrimental effects. Moreover, Ang II seems to play roles in the regulation of insulin secretion by the pancreatic β-cell and insulin sensitivity by peripheral tissues, which are two critical factors contributing to the development of type 2 diabetes. Accordingly, inhibiting Ang II produced beneficial effects on individual organs and throughout the body. Therefore, the present review discusses the role of Ang II in particular organs during normal physiological conditions as well as in type 2 diabetes.