In order to clarify the anti-hyperglycemic and anti-hyperlipidemic actions of traditional Chinese medicines, experiments were carried out with experimentally diabetic rats induced by cyproheptadine treatment. The following results were obtained: 1) Dai-saiko-to decreased the blood glucose level at 30, 60 and 120 min after glucose loading in the tolerance test; and the drug tended to increase serum insulin level and increased the ratio (glucose/insulin) at 120 min after the glucose loading. A significant decrease in serum total cholesterol was observed in the high fat diet-treated rats. 2) Hatimi-zio-gan also decreased the blood glucose level at 30 and 120 min after glucose loading. The drug did not lower the serum insulin, but rather increased the glucagon level at 120 min after the loading. The serum lipid level was not reduced by the drug. 3) Byakko-ka-ninzin-to also increased serum glucagon at 120 min, but no change of glucose and lipid in the sera under the above experimental conditions was observed. Such experimental results suggest that Dai-saiko-to might exert an effect that can improve the pathological conditions of diabetes mellitus.