Abstract: Objective To investigate the relationship between Diabetic Retinopathy(DR) and Level of Blood Glucose.Methods In the non conditinol case control study,the factors for the occurrence of DR were screened by Logistic regression analysis.Results Five significant independent factors for the occurrence and development of DR were screened out,which were urinary micro albumin excretion index(ALB/Cr),blood glucose before breakfast,glycosylated hemoglobin(HbA_1c),neural medical history and course of diabetes mellitus(DM).Conclusion The suggestible threshold value of blood glucose before breakfast is 7.90mmol/l at which we can prevent the occurrence of DR;at 7.15mmol/L,occurence of DR can be strictly controlled.