Objective To study the blood glucose changes in diabetic rats induced by alloxan monohydrate, and to assess the influence of blood glucose changes on research with this animal model. Methods The diabetic rat models were made by tail vein injection of aUoxan monohyclrate. The fasting and non-fasting blood glucose levels and urine glucose level were measured. Results The non-fasting blood glucose level became stable after 10 days and maintained a relatively high level for 120 days after aUoxan monohydrate administration. The fasting blood glucose level was varying continuously. Conclusion The diabetic rat models axe stable for four months at least. When this animal model is used to evaluate the therapeutic effect of a drug, the nonfasting, but not the fasting blood glucose level should be used as an indicator for observation.