Utility of urinary biomarkers as a diagnostic tool for early diabetic nephropathy in patients with type 2 diabetes mellitus

Renal tubulo-interstitial damage has an important role in the pathogenesis of early diabetic nephropathy. Urinary biomarkers can help in the detection of early nephropathy in type 2 diabetic patients. The aim of this study was to estimate the levels of urinary neutrophil gelatinase associated lipocalin (NGAL) and cystatin-C in type 2 diabetic patients with early diabetic nephropathy & to compare them with diabetic patients without nephropathy and to correlate urinary NGAL and cystatin-C levels with microalbuminuria in them. Cross-sectional comparative study. The study was conducted on 126 patients with type 2 diabetes along with 30 control subjects attending the outpatient care department of a tertiary care teaching hospital. There were 3 study groups-diabetic patients with microalbuminuria, diabetic patients without albuminuria and control subjects who were non-diabetic without any renal disease. Details on duration of diabetes and glycemic status were obtained from the patients. Urine examination was done for subjects in all the groups to look for microalbuminuria along with estimation of NGAL and cystatin-C levels. Samples were stored at −20 °C in the deep freezer. Urinary NGAL and cystatin-C levels were significantly elevated in patients with microalbuminuria (228.18 & 3.23 ng/ml) as compared to those without albuminuria (146.12 & 2.61 ng/ml) and in control subjects (26.56 & 0.30 ng/ml). Urinary NGAL and cystatin-C levels showed a linear correlation with microalbuminuria in diabetic patients. Urinary NGAL and cystatin-C levels were increased in type 2 diabetic patients with early diabetic nephropathy as compared to patients without nephropathy. Urine NGAL and cystatin-C levels also showed a positive correlation with microalbuminuria (urine albumin-creatinine ratio) in patients with type 2 diabetes mellitus.