Evaluation of serum Cystatin C as a predictor of eGFR in type 2 diabetic patients with nephropathy

Background: Diabetic nephropathy (DN) is the leading cause of chronic kidney disease (CKD) worldwide. Objective: To evaluate serum Cystatin C as a predictor of eGFR in type 2 diabetic patients with nephropathy. Methods: A cross-sectional analytical study was conducted at the Department of Nephrology, Liaquat University of Medical & Health Sciences, Jamshoro, Pakistan, from 10th March to 9th September 2023. Patients with type 2 diabetes (T2D) for more than five years, both males and females, 30 to 65 years of age, and with nephropathy for the last 2 years were included in the study. Serum creatinine, serum Cystatin C (Cys-C), fasting blood sugar (FBS), glycated hemoglobin A1c (HbA1c), total protein, and albumin were measured. A spot urine sample was collected to analyze total urinary protein, albumin, and creatinine levels. The estimated glomerular filtration rate (eGFR) was calculated using the CKD Epidemiology Collaboration (CKD-EPI) equation. One-way ANOVA, Pearson correlation test, and Linear regression analysis were done to analyze the data. Results: A total of 113 patients were analyzed, with a mean age of 55.5±6.1 years. The mean duration of T2D was 12.0±5.3 years. The mean HbA1c level was 9.1±1.3%. Based on Cys-C levels, the mean eGFR was 71.33±24.8 mL/min/1.73m². Among the participants, 43(38.1%), were suffering from Stage II, 32(28.3%) from Stage I, 32(28.3%) from Stage III, and 6(5.3%) from Stage IV CKD. A majority of 50(44.2%) of study participants had microalbuminuria. A statistically significant (p<0.001) negative correlation between eGFR and Cys-C level was observed among the study participants. Serum Cystatin C is a significant (<0.05) predictor of eGFR. Conclusion: Serum Cystatin C was a significant predictor of eGFR in type 2 diabetic patients with nephropathy. The strong negative relationship between Cystatin C and eGFR supports its potential role as a valuable marker for assessing renal function in diabetic patients.