Objective To investigate the effects of peroxisome proliferator-activated receptor γ (PPARγ) signal pathway activation on cardiac fibrosis in diabetic rats,and the effects on cardiac remodeling and cardiac function at early stage of diabetes.Methods Forty-eight SD rats were divided into 3 groups: control,diabetic,and pioglitazone (Piog) treatment groups,with 16 in each group.Except control group,other 32 rats received abdominal injection of streptozotocin (STZ) to prepare type 1 diabetic models.After 14 weeks,fibrosis indices were determined;cardiac remodeling and cardiac function were evaluated by echocardiography and intraventricular pressures indices.Results After 14 weeks,compared with control group,hydroxyproline concentration in diabetic group significantly increased (P<0.05).Sirius red staining showed that cardiac fibrosis was more obvious in diabetic group than in control group,and significantly lessened in Piog group than in diabetic group.In diabetic group,the left ventricular systolic pressure reduced significantly and the left ventricular end-diastolic pressure increased significantly,which were obviously improved by Piog administration.Conclusion Piog treatment can alleviate cardiac fibrosis in diabetic rats and improve cardiac remodeling and cardiac function at early stage of diabetes.