AIM:To investigate the expression of cytokines:vascular endothelial growth factor(VEGF),platelet-derived growth factor(PDGF),angiogenin,endothelin-1(ET-1)in venous blood of diabetic retinopathy rat models in early stage.METHODS:GK rats were chosen as the DR animal models and the normal Wistar rats as the control group.The rats were divided into 3 groups:aged 2,4,6 months old.Concentration of VEGF,PDGF-BB,angiogenin,ET-1 in venous blood were detected by ELISA.RESULTS:The expression of VEGF,angiogenin,ET-1 in venous blood of GK rats was significantly higher than that of normal Wistar rats(P<0.05).The concentration of ET-1 in venous blood of GK rats became higher as animal grew(P<0.05).There were no statistical differences in PDGF-BB of venous blood between the groups of rats.CONCLUSION:The expression of VEGF,ET-1,angiogenin in venous blood may be used to follow up the early stage of DR.Because of the obvious fluctuation of PDGF-BB in venous blood,we are not sure of its value.