Background: Diabetic retinopathy (DR) is one of the diabetic microvascular complica-tions, which is also one of the important causes of blindness in adults. Objective: To investigate the association between proliferative retinopathy and serum bile acid lev -el in patients with type 2 diabetes mellitus (T2DM). Methods: Three hundred and thirty-six patients with T2DM were included, of which, 229 had a his-tory of more than 10 years without diabetic retinopathy (no diabetic retinopathy, NDR) and 107 had proliferative diabetic retinopathy (PDR). The baseline characteristics of the two groups were compared. According to the level of bile acid, the patients were divided into low, medium and high bile acid groups. The ratio of proliferative retinopathy in each group was compared. The presence of retinopathy was taken as the dependent variable, and the significant variables were analyzed by logistic regression. Results: The level of total bilirubin and bile acid in the NDR group was significantly higher than that in the PDR group, while the levels of triglyceride, cholesterol and LDL-C were significantly lower than that in the PDR group (P<0.05). With the increase of bile acid level, the proportion of proliferative retinopathy decreased. Logistic regression analysis showed that bilirubin and bile acid were protective factors of diabetic retinopathy, while SBP, LDL-C and UAER were risk factors of diabetic retinopathy. Conclusion: Bile acid might be a protective factor for diabetic retinopathy in T2DM, which might be a potential therapeutic role in retinal disorders.