Black Adzuki Bean (Vigna angularis) Extract Protects Pancreatic β Cells and Improves Glucose Tolerance in C57BL/6J Mice Fed a High-Fat Diet.

Adzuki beans have long been cultivated as a food and folk medicine in East Asia. In this study, we investigated the effect of black adzuki bean (BAB) extract on pancreatic cells and determined their mechanism of action in impaired glucose tolerance in an animal model of type 2 diabetes. In addition, we performed functional gene annotation analysis to identify genes related to the regulation of glucose metabolism and insulin response. Treatment of pancreatic β cells with BAB extract (0.2 mg/mL) led to tolerance of the high glucose-induced glucotoxicity, resulting in a similar viability as cells maintained in normal glucose media. In addition, dietary supplementation with BAB extract significantly (P < .05) improved hyperglycemia and homeostasis model assessment of insulin resistance index (HOMA-IR) in high-fat diet-induced glucose-intolerant obese C57BL/6J mice. Our results suggest that BAB extract ameliorates hyperglycemia and glucose intolerance, and lowers HOMA-IR by regulating insulin secretion and response, and by maintaining the integrity of pancreatic β cells exposed to hyperglycemic conditions.