Abstract: Objective To establish a rat model of gestational insulin resistance similar to human gestational diabetes mellitus by feeding a high-fat diet. Methods Twelve SPF-grade unproductive female SD rats were randomly divided into a normal diet group （NP group） and a high-fat diet group （HP group）. Before and after pregnancy, the NP group was fed with a normal diet, while the HP group with a high-fat diet. The body weight and blood glucose were measured before dietary intervention, during pregestational high-fat diet period, and during pregnancy. Fasting glucose tolerance test was performed on the 18^th day of pregnancy. Results On the 5^th, 12^th, and 18^th day of pregnancy, fasting blood glucose in HP group was significantly higher than that in NP group （P < 0.05 or P < 0.01）. The blood glucose in HP group was significantly higher than that in NP group at all time points of oral glucose tolerance test （P < 0.05 or P < 0.01）. The levels of insulin, insulin resistance index, free fatty acid, low density cholesterol, and triglyceride in HP group were significantly higher than those in NP group on the 18^th day of pregnancy （P < 0.05 or P < 0.01）. Conclusions In the SD rat model of gestational diabetes mellitus induced by a high-fat diet, the blood glucose of pregnant rats increased from early pregnancy and maintained highly until late pregnancy, and there was obvious insulin resistance. These characteristics were similar to the pathogenesis of human gestational diabetes mellitus.

Key words: Gestational diabetes mellitus, High-fat diet, Insulin resistance, Animal model