Role of red grape polyphenols as antidiabetic agents

The worldwide incidence of diabetes mellitus has reached alarming proportions. Persistent hyperglycemia due to impaired insulin activity and/or insulin resistance inversely affects the retina, cerebrovascular system, kidney, peripheral limbs, and other parts of the body, which leads to life-threatening complications. The causal role of oxidative stress in the development and progression of diabetic complications has been emphasized. Polyphenols present in natural products have gained much attention in recent decades in preventive studies against diabetes-associated pathologies. In the present review, we provide a comparative update on the role of quercetin, myricetin, and resveratrol—the major polyphenols present in red grapes—in intervening with diabetic complications, and a brief highlight on the molecular mechanisms underlying oxidative stress mediated hyperglycemia.