Serum NGAL and Cystatin C Comparison With Urinary Albumin-to-Creatinine Ratio and Inflammatory Biomarkers as Early Predictors of Renal Dysfunction in Patients With Type 2 Diabetes

Introduction: Diabetic nephropathy is associated with specific histological changes. Early detection of poor glomerular and tubular function can be achieved with biomarkers of diabetes. The aim of this study was to evaluate the accuracy of kidney dysfunction biomarkers in type 2 diabetes (T2D). Methods: Patients with T2D were grouped according to their glycated hemoglobin level. Patients' urine and blood samples were taken to measure cystatin C (CysC), neutrophil gelatinase-associated lipocalin, beta-trace protein levels, and the first morning void albumin-to-creatinine ratio. Patients in the end stage of renal disease or receiving dialysis were not included. Receiver operating characteristic curves were generated, and the areas under the curve were compared with the performance of the biomarkers used to evaluate kidney dysfunction in T2D. Results: Ninety patients with T2D were chosen. CysC was positively correlated with creatinine (P < 0.001), estimated glomerular filtration rate (P < 0.001), and urinary beta-trace protein (P = 0.01). The area under the curve was 0.635 for CysC, 0.621 for serum neutrophil gelatinase-associated lipocalin, and 0.660 for the albumin-to-creatinine ratio. A crude logistic regression model showed a positive association between serum CysC (P = 0.01) and serum neutrophil gelatinase-associated lipocalin (P < 0.001). A linear regression model showed a positive association between serum CysC, creatinine, and estimated glomerular filtration rate (P < 0.001) but did not show a positive association with glycated hemoglobin (P = 0.892). Discussion: Neutrophil gelatinase-associated lipocalin and serum CysC were positively associated with the presence of renal dysfunction and had better performance on receiver operating characteristic analysis than the other markers evaluated in patients with T2D without kidney dysfunction.