| Background and objective:Diabetic retinopathy(DR)has become the main cause of adult non traumatic blindness.The pathophysiological mechanism of DR is complex,and oxidative stress and inflammation play an important role in it.Bilirubin is the main metabolite of heme,which has a strong ability of scavenging oxygen free radicals.Therefore,bilirubin may have an important protective effect on DR.This study aims to explore the correlation between serum bilirubin level and retinopathy in patients with type 2diabetes mellitus.Methods:A total of 702 patients with type 2 diabetes who were admitted to the Department of Endocrinology of the First Affiliated Hospital from November 2018 to November 2020 were included in this study,including 351 patients with retinopathy(DR)and 351 patients without retinopathy(NDR).The general information of each subject was collected,including gender,age,course of disease,history of disease,family history,height,weight,etc.,and the indexes of serum bilirubin,blood glucose,blood lipid,renal function,myocardial enzyme spectrum and so on were detected by automatic biochemical analyzer.Multivariate Logistic regression was used to analyze the correlation between serum total bilirubin(TBIL),direct bilirubin(DBIL)and indirect bilirubin(IBIL)in type 2 diabetic retinopathy,and to further explore whether other influencing factors have modifying effects on bilirubin and retinopathyResults:The levels of total bilirubin,direct bilirubin and indirect bilirubin in DR group were 7.4(±3.8)μmol/L,2.8(±1.6)μmol/L and 4.6(±2.7)μmol/L,respectively,which were significantly lower than those in NDR group(9.5(±4.8)μmol/L,4.0(±2.0)μmol/L and 5.6(±3.2)μmol/L,respectively,and the differences between groups were statistically significant(P<0.001).There was an independent negative correlation between TBIL,DBIL,IBIL and diabetic retinopathy.After adjustment for age,sex,systolic blood pressure,body mass index,smoking,Hb A1 c,serum creatinine,and cholesterol levels,the odds ratio(OR)and 95% confidence intervals(95%CI)for diabetic retinopathy were 0.89(OR: 0.89,95%CI: 0.85-0.94;P<0.001),0.74(OR:0.74,95%CI: 0.65-0.84;P<0.001),0.86(OR: 0.86,95%CI: 0.80-0.92;P < 0.001).The levels of TBIL,DBIL and IBIL were divided into three groups according to the trisle method: the first trisle group(the lowest trisle group),the second trisle group and the third trisle group(the highest trisle group).The risk of diabetic retinopathy was significantly lower in the highest score group than in the lowest score group(OR and 95%CI were 0.31(0.19-0.49),0.27(0.16-0.44),and 0.35(0.22-0.57),respectively).Furthermore,stratified analysis showed that the effect of bilirubin on retinopathy was not affected by age,sex,body mass index,total cholesterol,and Hb A1 c.Conclusion:These data suggest that a slight increase in bilirubin levels within the normal physiological range is significantly associated with a decreased risk of retinopathy in patients with type 2 diabetes,independent of other traditional risk factors,suggesting that bilirubin may have a protective effect on diabetic retinopathy.However,further studies are needed to confirm this. |
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