Abstract: Objective  To explore  the relationship between serum levels of bilirubin  and diabetic retinopathy (DR).Methods  293 patients with type 2 diabetes admitted to  the hospital and diagnosed were selected. According to the fundus examination,  the patients were divided into nondiabetic retinopathy group (NDR) (n=146)  and diabetic retinopathy group (DR) (n=147). DR group was divided into nonproliferative diabetic retinopathy group (NPDR) (n=103) and  proliferative diabetic retinopathy group(PDR)  (n=44).The clinical data of  NDR, NPDR and PDR  groups  were analyzed and compared. According to the quartile of  total bilirubin, the groups were divided into Q1, Q2, Q3 and Q4, and the relationship between total bilirubin(TBIL) and DR prevalence was analyzed.Results  Compared with  NDR group, both  disease duration and systolic blood pressure in  NPDR group and PDR group were increased (P<0.05), and the disease duration and systolic blood pressure in PDR group were higher than those in  NPDR group (P<0.05).  Compared with  NDR group, TBIL, direct bilirubin(DBIL) and  Cpeptide 2 hours meal(2 hCP) in NPDR group and PDR group were  all decreased, and TBIL, DBIL, indirect bilirubin(IBIL) and 2 hCP  in  PDR group were lower than those in NPDR group (P<0.05). Compared with NDR group, IBIL of PDR group was lower than that of NDR group(P<0.05).Compared with NDR group, FPG, 2 hPG, HbA1c and  TC in NPDR group and PDR group were all  increased, and  FPG, 2 hPG, HbA1c and  γGGT in PDR group were higher than those in NPDR group (P<0.05).  Compared with NDR group, γGGT  in  PDR group was higher than that in  NDR group (P<0.05). Multiple  ordered  Logistic regression analysis  showed that  TBIL and 2 hCP were protective factors for DR. Duration of disease, systolic blood pressure, FPG, 2 hPG, HbA1c and γGGT were the risk factors for DR.The prevalence of DR varied with different TBIL levels. With the increase of TBIL levels, the prevalence  of   DR showed a decreasing trend(P<0.05).Conclusion  The decrease of  TBIL level is  correlated with the increased risk of DR, and can be used as a potential biomarker to predict the risk  of DR  in DM patients.For patients with low serum bilirubin, close monitoring of  2 hCP level and strengthening monitoring and management of blood glucose, HbA1c, SBP and  γGGT  are of great significance for the prevention of DR.

Key words: diabetes mellitus, type 2; , diabetic retinopathy, bilirubin; , oxidative stress