This study evaluated effects of Yanggyuksanhwa-tang(YST) on diabetic rats. Diabetic condition in rats was induced by streptozotocin injection. Then control effect of YST was observed with changes of serum glucose, insulin, and triglyceride levels and hepatic glucokinse activity. YST treatment was resulted significant decrease of high serum glucose level of diabetic rats induced by streptozotocin at 5th day of YST treatment. YST treatment was resulted increase of low serum insulin level of diabetic rats induced by streptozotocin, but it was not significant statistically. YST treatment was resulted significant decrease of high serum triglyceride level of diabetic rats induced by streptozotocin at 3rd and 5th of YST treatment. YST treatment was resulted significant increase of low hepatic glucokinase activity of diabetic rats induced by streptozotocin at 5th day of YST treatment. These results suggest that YST has effects on serum glucose control against cerebral inchemic damage under diabetic condition.