Troglitazone, a PPAR-gamma agonist, is a new drug for type 2 diabetes. The drug decreases blood glucose via enhancing insulin action. Recently Sankyo pharmaceutical company is warning severe hepatotoxicity by troglitazone. It recommends to examine liver function every month in diabetic patients treated with the drug in order early to find drug-induced hepatitis. In Japan 153 diabetic patients treated with the drug developed severe hepatitis and 8 of them died of drug-side effects. Quinone metabolite of troglitazone predominantly in the liver to a sulfate conjugate and activation of PPAR gamma and PXR(pregnane X receptor) by troglitazone are supposed to be factors of hepatotoxic mechanism.