The effects of clofibrate (120 mg/kg) on the blood levels of glucose, lactate, pyruvate, free fatty acids (FFA) , triglycerides (TG), cortisol, triiodothyronine (T3), tetraiodothyronine (T4) , calcium and potassium of adult male diabetic rats were studied for four weeks . Moreover, the effects of four weeks treatment with clofibrate on the oral glucose tolerance were investigated. Results showed that administration of clofibrate significantly decreased the blood glucose levels to 190 , 165 and 160 mg/dl after the1^st  ,2^nd ,3^rd and 4^th week of treatment vs 230 mg/dl of control. Moreover, clofibrate improved the glucose tolerance in STZ - diabetic rats after four weeks of treatment in comparison with the control diabetic rats. There is a reduction in the area under the glucose curve recording 59550± 3440 vs 79200 ± 5060 mg, min/ dl of control value. Clofibrate decreased the blood levels of FFA , TG, T4, whereas, it increased that of cortisol. The plasma levels of both lactate and pyruvate were reduced all over the time course of treatment. Potassium biood levels were significantly increased to 26.9, 25.8, 27.6 and 28.4 mg/dL after the 1^st, 2^nd, 3^rd and 4^th week of treatment respectiviely. In conclusion, the capability of the antihyperlipidemic agent, clofibrate, to reduce the blood glucose levels and to improve glucose tolerance in STZ- diabetic rats may be in part due to its ability to reduce the blood levels of FFA,TG, lactate and pyruvate and in part to the increasing of potassium plasma levels. All these changes could play a major role in reduction of the rate of gluconeogenesis and consequently reducing the hepatic glucose production (HGP) that may participate in the above actions of clofibrate on blood glucose.