CYP1A2 and diabetes mellitus: Our present work found that except the activities of hepatic CYP2B and 3A, the activities of hepatic CYP1A2, 2E1, 2C and 4A in the DC rats were all increased significantly as compared with those in the NC rats, suggesting that in the state of diabetes, the metabolic clearance of liver on the substrate drugs of CYP1A2, 2E1, 3C and 4A should be increased, which might affect the therapeutic action of drugs.