The effects of flavone extracted from Ipomoea batatas leaf (FIBL) on body weight, blood glucose, serum lipid profiles, serum insulin and free radicals in rats with non-insulin dependent diabetes mellitus (NIDDM) were studied. FIBL treatment (25, 50, 100 mg kg−1) for 2 weeks resulted in a significant decrease in the concentration of plasma triglyceride (TG), plasma cholesterol (TC) and weight in NIDDM rats. Furthermore, FIBL markedly decreased fasting plasma insulin level, blood glucose (FBG) level, low-density lipoprotein cholesterol (LDL-C), and malondialdehyde (MDA) levels and significantly increased the Insulin Sensitive Index (ISI) and superoxide dismutase (SOD) level in NIDDM rats. In addition, flavone extracted from I. batatas leaf did not show any physical or behavioural signs of toxicity. More significantly, our data demonstrate the FIBL at the dose of 50 mg kg−1 body weight exhibited the optimal effect. The above results suggest that flavone extracted from I. batatas leaf could control blood glucose and modulate the metabolism of glucose and blood lipid, and decrease outputs of lipid peroxidation and scavenge the free radicals in non-insulin dependent diabetic rats.