Angiotensin II has been reported to insulin secretion in beta cells. Angiotensin II indirectly improves insulin secretion in beta cells via vasoconstriction and reduced islet blood flow. Chronic exposure to high glucose or high fat increases expression of AT1R (angiotensin type 1 receptor), leading to reactive oxidative stresses, inflammation, and apoptosis in beta cells, finally decreased insulin formation and secretion. Some studies showed the beneficial effect of blocking AT1R on insulin secretion and beta cell proliferation in animal models using angiotensin receptor blocker (ARB). Furthermore, 26 weeks of valsartan treatment improved insulin secretion in humans with impaired glucose regulation.