Streptozotocin (STZ) is used to induce experimental diabetes in rodents. There is however, controversy as to whether STZ induced diabetes models type 1 or 2 diabetes. We show that the grade of STZ-induced hyperglycemia in male CD1 mice is dependent on STZ dose. A single injection of high dose (130 or 150 mg/Kg body weight) or multiple injections (2, 3, 4 or 5) of low dose (40 mg/Kg body weight) STZ was administered intraperitonealy in non-fasted mice. Blood glucose and body weight were measured over 21 days for high dose and 21 and 28 days for low dose administration. On day three, high dose treatment produced hyperglycemia and body weight loss in comparison to mice without STZ, however unstable hyperglycemias and several deaths were observed during treatment. Hyperglycemia and body weight loss were seen with three or more injections of STZ at 21 days, whereas 4 and 5 injections produced severe hyperglycemia but not death. Mild hyperglycemia (250-450 mg/dL) was seen after 28 days following three injections of STZ. Therefore we concluded that a high dose STZ produces severe hyperglycemia in mice similar to a type 1 diabetic, and three successive administrations of STZ induces mild hyperglycemia in mice similar to type 2 diabetics.