Cystatin C, Neutrophil Gelatinase-associated Lipocalin, and Pro-atrial Natriuretic Peptide as Biomarkers in the Assessment of Diabetic Nephropathy Patients

Background: Diabetic nephropathy (DN) is a significant microvascular complication linked with diabetes mellitus which leads to chronic kidney disease worldwide. Conventional biomarkers, namely, serum creatinine and albuminuria often fail to detect early renal impairment. Aim: The study aimed to compare the utility of serum cystatin C, neutrophil gelatinase-associated lipocalin (NGAL), and pro-atrial natriuretic peptide (ANP) for assessing the severity of DN. Materials and Methods: This prospective, observational study was conducted on 52 DN cases and 52 controls. Clinical and laboratory parameters of all were assessed at baseline. Serum creatinine, cystatin C, NGAL, and pro-ANP of cases were measured at baseline, 6 months and 12 months. Statistical analysis, including group comparison, correlation and regression analysis, receiver operating characteristic (ROC) analysis, and longitudinal analysis, was done on IBM SPSSv26. Results: At baseline, cases had significantly higher serum creatinine, cystatin C, and NGAL than controls. Pro-ANP was higher in cases but not significant. A significant Pearson’s correlation appeared between cystatin C ( r = −0.852), creatinine ( r = −0.833), pro-ANP ( r = −0.553), and estimated glomerular filtration rate (eGFR) (all P < 0.001). No significant correlation was observed between NGAL and eGFR. ROC analysis showed that cystatin C had the highest diagnostic accuracy (area under the curve = 0.995, P < 0.001). Time trend analysis highlighted a significant increase of cystatin C, pro-ANP, and serum creatinine ( P < 0.001), but not for NGAL ( P = 0.093), with increasing renal impairment over 12 months. Conclusion: Cystatin C demonstrated strongest correlation with eGFR and highest diagnostic accuracy. Time trend analysis revealed significant increase in cystatin C level over 12 months, highlighting its potential role as biomarker for monitoring DN patients.