The diabetic state is considered to be one of the risk factors of drug-induced liver injury (DILI) because of the lower levels of glutathione for detoxification by conjugation with drugs. Carbamazepine (CBZ) -induced hepatotoxicity in humans is rare and unpredictable with the present state of knowledge, but it is somehow related to disturbance of glutathione metabolism, although data in this regard are limited. In order to estimate the potential risk of DILI in patients with type 2 diabetes mellitus (T2DM), we investigated the liver injury from CBZ, which is often used in the treatment of painful diabetic neuropathy in diabetic patients, using SD rats and Spontaneously Diabetic Torii-Lepr^fa (SDT fatty) rats as a model for human T2DM. The SDT fatty rats appropriately mimic the diabetic state in humans and have similar profiles of glucose metabolism, hepatic function tests and glutathione synthesis to those in patients with T2DM. Short-term oral dosing with CBZ to the SDT fatty rats revealed that liver injury was detected in the SDT fatty rats but not in the SD rats and the difference was considered to be due to lower hepatic detoxification of the metabolites of CBZ by depleted hepatic glutathione synthesis. In conclusion, the potential for CBZ to induce liver injury is considered to be higher in diabetic patients than in non-diabetic humans.