AIM: Effects on insulin sensitivity of Die-Huang-Wan, the herbal mixture widely used to treat diabetic disorder in Chinese traditional medicine, were investigated in vivo. METHODS: The obese Zucker rats were employed as insulin-resistant animal model. Also, insulin-resistance was induced by the repeated intraperitoneal injections of long-acting human insulin at 0.5 U/kg three times daily into adult male Wistar rats. Insulin resistance was identified using the loss of tolbutamide (10 mg/kg) or electroacupuncture (EA)-induced plasma glucose lowering action. The plasma glucose concentration was examined by glucose oxidase assay. RESULTS: The plasma glucose-lowering action induced by tolbutamide was significantly enhanced in obese Zucker rats receiving the repeated administration of Die-Huang-Wan at dosage of 26 mg/kg for 3 d. Furthermore, administration of Die-Huang-Wan delayed the formation of insulin resistance in rats that were induced by the daily repeated injection of human long-acting insulin at 0.5 AIM: Effects on insulin sensitivity of Die-Huang-Wan, the herbal mixture widely used to treat diabetic disorder in Chinese traditional medicine, were investigated in vivo. METHODS: The obese Zucker rats were employed as insulin-resistant animal model. Also, insulin -resistance was induced by the repeated intraperitoneal injections of long-acting human insulin at 0.5 U / kg three times daily into adult male Wistar rats. Insulin resistance was identified using the loss of tolbutamide (10 mg / kg) or electroacupuncture (EA) - induced plasma glucose lowering action. The plasma glucose-lowering action induced by tolbutamide was significantly enhanced in obese Zucker rats receiving the repeated administration of Die-Huang-Wan at dosage of 26 mg / kg for 3 d. Furthermore, administration of Die-Huang-Wan delayed the formation of insulin resistance in rats that were induced by the daily repeated injection of human long-acti ng insulin at 0.5