Relationship between serum bilirubin and diabetic kideny disease in patients with type 2 diabetes

Objective To approach the relationship between serum bilirubin level and diabetic kideny disease in patients with type 2 diabetes mellitus(T2DM).Methods 789 T2DM patients were classified into normoalbuminuria group(urinary albumin excretion less than 30 mg per 24 h),microalbuminuria group(urinary albumin excretion range from 30 to 300 mg per 24 h) and macroalbuminuria group(urinary albumin excretion more than 300 mg per 24 h) according to the degree of urinary albumin excretion.We chose 168 healthy adults randomly as the control group.The difference in serum bilirubin among groups and the correlation between serum bilirubin and diabetic nephropathy were analyzed.Results T2DM group had higher levels of serum total bilirubin,direct bilirubin and unconjugated bilirubin significantly than those of the control group(P0.01 or P0.05).The total bilirubin and unconjugated bilirubin levels of the microalbuminuria group were lower compared with those of the normoalbuminuria group(P0.01,P0.05),while there was no significant difference in the direct bilirubin(P0.05).Compared with the other two groups,the macroalbuminuria group had lower serum total bilirubin,direct bilirubin as well as unconjugated bilirubin,difference was significant(P0.01).The correlation analysis showed that the correlation coefficients of urinary albumin to serum total bilirubin,direct bilirubin and unconjugated bilirubin were r=-0.108,P0.01,r=-0.068,P0.05,r=-0.106,P0.05,respectively.Besides,we found that the correlation coefficients of glomerular filtration rate to serum total bilirubin,direct bilirubin and unconjugated bilirubin were r=0.196,P0.001,r=0.074,P0.05,r=0.12,P0.05,respectively.Conclusion Bilirubin may be a protective factor of the kidneys in patients with T2DM.It is very important to take active antioxidant treatments in early stage of T2DM to prevent the development of diabetic kidney disease.