Vascular complications are major causes of disability and death in patients with diabetes mellitus.Epidemiological studies indicate that tea consumption may reduce the risk of cardiovascular disease.To investigate the preventive effects of tea on hyperglycemia and vascular complications of diabetes, we report the extraction and composition as well as the hypoglycemic and vasculoprotective effects of black tea extract (BTE), green tea extract (GTE), and dark tea extract (DTF).