OBJECTIVE To evaluate the antihyperglycemic,hypolipidemic and antioxidant activities of total saponins extracted from Aralia taibaiensis (SAT) in experimental type 2 diabetic mellitus (T2DM) rats.METHODS Acute toxicity study was carried out in rats to determine the safely oral dose of SAT.Rats were induced T2DM by combination administration of streptozotocin (65 mg/kg,intravenously) with nicotinamide (110 mg/kg,intraperitoneally).Then,SAT was given orally to the diabetic and normal rats at 80,160 and 320 mg/kg doses for a series of 28 days,respectively.As a positive control,600 μg/kg glibenclamide was also administered to the diabetic rats simultaneously.Effect of SAT and glibenclamide on fasting blood glucose (FBG),body weight and food intake was determined on a weekly basis.At the end of study,fasting blood sample was collected to test the levels of glycosylated haemoglobin (HbA1c),fasting serum insulin (FSI),blood lipid profile,biochemical indexes and antioxidant indices.Also,the tissues of pancreas were excised for histopathological examination.RESULTS Oral administration of SAT did not exhibit toxicity and death at a high dose of 2000 mg/kg.SAT dose-dependently improved the symptoms of diabetic rats and showed antihyperglycemic activity.At the dose of 320 mg/kg,SAT exhibited maximum antihyperglycemic,hypolipidemic and antioxidant effects on the diabetic rats,comparable to 600 μg/kg glibenclamide.The high dose of SAT not only significantly (P<0.05) reduced elevated FBG,HbA1c,food intake,creatinine,urea,ALT and AST levels,and significantly (P<0.05) increased body weight and FSI level compared with diabetic control rats,but also significantly (P<0.05) reversed abnormal status of lipid profile and antioxidant parameters towards near normal levels.Moreover,the islet cells were also restored to near normal.However,SAT did not produce any effect on the normal rats.CONCLUSION SAT had excellent antihyperglycemic,hypolipidemic and antioxidant activities in T2DM rats and might be a promising drug in the therapy of diabetes mellitus and its complications.