The purpose of this study was to assess the effects of Cordyceps militaris extract supplementation on the improvement of blood glucose, lipid compositions and hepatic functional enzyme activities in the serum of streptozotocin(STZ, 50 mg/kg BW,IP injection)-induced diabetic rats fed the experimental diets for 5 weeks. The concentrations of blood glucose and lipid compositions(total cholesterol, β-lipoprotein, free cholesterol, cholesteryl ester, triglyceride and phospholipid) and atherosclerotic index in serum were significantly lower in the DM+CM group than in the DM group, whereas the ratio of HDL-cholesterol concentration to total cholesterol in the DM+CM group were higher than in the DM group. The activities of hepatic functional enzymes(aminotransferase, LDH and ALP) in serum were lower in the Cordyceps militaris extract administration group(group DM+CM) than in the hyperglycemic DM group. The results shown above suggested that Cordyceps militaris extract supplementation effectively improves blood glucose and atherosclerosis in the serum of diabetic rats.