Association between serum bilirubin and estimated glomerular filtration rate in diabetic patients with chronic kidney disease

Background and objectives: Hyperglycemia induces oxidative stress in diabetic patients by increasing reactive oxygen species production, which ultimately damage the cells and cause micro and macrovascular complications including diabetic nephropathy. Increased serum bilirubin level, within physiological range, can inhibit oxidative stress; thereby, preventing development of diabetic nephropathy. The aim of this study was to find out association between serum bilirubin and estimated glomerular filtration rate (eGFR) in diabetic patients with or without chronic kidney disease (CKD). Materials and method: Both male and female participants aged 30 to 60 years were enrolled in the study. Enrolled participants included healthy individuals (Group-1), diabetic patients without CKD (Group-2) and diabetic patients with CKD (Group-3). Clinical and biochemical parameters namely blood pressure, body mass index (BMI), fasting blood glucose (FBG), HbA1c, eGFR, serum bilirubin and spot urine ACR were measured by appropriate methods. Pearson’s correlation coefficient, ANOVA and multiple linear regression models were used to analyze the data. Result: Total 189 respondents were enrolled in 3 study groups. Each group consisted of 63 cases. Of the 63 cases in Group-3, 49 and 14 belonged to CKD stage 3 and stage 4 respectively. The mean (± SD) serum bilirubin levels of healthy individuals, diabetic patients without CKD and diabetic patients with CKD were 0.66 ± 0.31, 0.64 ± 0.21, 0.46±0.18 mg/dL respectively. Mean serum bilirubin was significantly low (p<0.001) in diabetic patients with CKD compared to healthy and diabetics without CKD. A Stepwise multiple regression analysis using eGFR as an objective variable adjusted for risk factors as explanatory variables, showed that serum bilirubin (β=0.323, p<0.001) was significantly associated with eGFR, in addition to age, BMI, HbA1c and urinary ACR. Conclusion: The study has demonstrated that low serum bilirubin level is associated with CKD in diabetic patients and it could be used as a simple marker for CKD in diabetics. IMC J Med Sci. 2024; 18(1):006. DOI: https://doi.org/10.55010/imcjms.18.006 *Correspondence: Tanzia Tahfim, Department of Biochemistry, Shaheed Monsur Ali, Medical College, Uttara, Dhaka-1230, Bangladesh. Email: tanzia.uamc@gmail.com