Objective To investigate the association of serum thioredoxin (Trx) and 3-nitrotyrosine (3 NT) levels with diabetic retinopathy (DR) in the elderly,in order to provide new evidence for clinical prevention and treatment of DR.Methods A total of 156 patients diagnosed with type 2 diabetes mellitus (T2DM) at the Department of Endocrinology were selected.Based on of fundus examination results,the patients were divided into the non-diabetic retinopathy group (NDR) (n=52),the nonproliferative diabetic retinopathy group (NPDR) (n =52) and the proliferative diabetic retinopathy group (PDR) (n=52),with 52 healthy people enrolled in the control group (CON).Solid phase enzyme linked immunosorbent assays (ELISA) were used to measure serum levels of Trx and 3-NT in all subjects.The results were statistically analyzed.Results The expression of Trx in the serum was the lowest in CON,followed by NDR,NPDR and PDR [[(324.1± 69.3) pg/L,(429.5±36.9) pg/L,(515.2±43.0) pg/L and (588.8±112.5) pg/L,respectively],and there were statistically significant differences between the groups (F=19.00,P=0.000).Similarly,the expression of 3 NT in the serum was the lowest in CON,followed by NDR,NPDR and PDR [(0.16±0.07) ng/L,(0.22±0.05) ng/L,(0.28±0.06) ng/L and (0.38±0.09) ng/L,respectively],and there were statistically significant differences between the groups (F=28.78,P=0.000).The expression levels of Trx and 3 NT in the serum were positively correlated with the severity of DR (r=0.64 and 0.66,respectively,P 0.001 for both).There was a correlation between serum Trx and 3-NT (r 0.71,P=0.001).Conclusions Serum levels of Trx and 3 NT are increased with the severity of DR,and they are positively correlated with the severity of DR.