Assessment of Cystatin C and Microalbumin as Biomarkers for Nephropathy in Patients with Type 2 Diabetes Mellitus

BACKGROUND Increased levels of urinary biomarkers can be detected in type 2 diabetic patients before the onset of significant albuminuria and may be used as an early marker of renal injury in diabetic nephropathy (DN) which would play a significant role for the effective management and treatment approaches in diabetic care. We wanted to evaluate cystatin C and microalbumin as effective early biomarkers in assessing nephropathy in patients with type 2 diabetes mellitus in this study. METHODS A cross-sectional study was conducted among 180 subjects grouped into healthy controls, clinically proven T2DM without nephropathy and type 2 DM with nephropathy comprising 60 participants in each group. Fasting and postprandial blood samples and urine samples were collected and analysed by standard methods. eGFR was calculated using CKD-EPI 2012 equation. IBM - SPSS version 20 was used for statistical analysis. RESULTS Diabetic nephropathy patients had significantly elevated serum cystatin C and microalbumin (2.43 ± 0.59, 700.5 ± 591.8 mg / L, respectively), compared to T2DM (0.98 ± 0.26, 63.7 ± 102.9 mg / L, respectively), and the control study subjects (0.81 ± 0.16, 11.15 ± 8.9 mg / L, respectively). Serum cystatin C showed AUC of 0.994 (95 % CI, 0.986 - 1.00) whereas microalbumin showed 0.944 (95 % CI, 0.907 - 0.981). Serum cystatin C showed a sensitivity of 96.7 % and a specificity of 91.7 % at a cutoff point of 1.34 mg / L whereas at a cut-off point of 138.5 mg / L for microalbumin, the sensitivity and specificity were 90 % and 83.3 % respectively. CONCLUSIONS Serum cystatin C and microalbumin both could be considered as markers for early detection of nephropathy in T2DM patients. The more prominent rise in serum cystatin C values provide an earlier diagnosis of diabetic nephropathy among T2DM patients. KEY WORDS Biomarker, Type 2 Diabetes Mellitus, Cystatin C, Diabetic Nephropathy, Microalbumin