Urinary monocyte chemoattractant protein-1 and vitamin D-binding protein as biomarkers for early detection of diabetic nephropathy in type 2 diabetes mellitus

Diabetic nephropathy is a serious complication of both type 1 and type 2 diabetes and, unless arrested, leads to end-stage renal disease. Therefore, early prediction and detection of DN would greatly benefit the disease management and delay its progression. The aim of this study is to evaluate the levels of urinary monocyte chemoattractant protein-1 (uMCP-1) and urinary vitamin D-binding protein (uVDBP) in type 2 diabetic patients with different degrees of diabetic nephropathy (DN) and to assess the value of uMCP-1 and uVDBP in the early detection of DN. Seventy-five type 2 diabetic patients with normoalbuminuria (n = 25), microalbuminuria (n = 25), macroalbuminuria (n = 25), and 25 healthy controls were included in this study. Urinary MCP-1 and VDBP levels were evaluated by enzyme-linked immunosorbent assay. A significant elevation in the uMCP-1 and uVDBP levels was found in macroalbuminuric (p < 0.001) and microalbuminuric (p < 0.01) diabetic patients compared to that in normoalbuminuric diabetic patients and control subjects (p < 0.001). Correlation study revealed that both uMCP-1 and uVDBP were significantly positively correlated to urinary albumin/creatinine ratio (r = 0.968, p < 0.001 and r = 0.973, p < 0.001, respectively), serum urea (r = 0.461, p = 0.001 and r = 0.456, p = 0.002, respectively), and serum creatinine (r = 0.475, p = 0.001 and r = 0.448, p = 0.004, respectively) and significantly inversely correlated to glomerular filtration rate (r = -0.983, p < 0.001 and r = -0.988, p < 0.001, respectively). Receiver operating characteristic (ROC) curve analysis of uMCP-1 and uVDBP levels for early diagnosis and detection of DN revealed that the cut-off value of uMCP-1 was 110 pg/mg with 92 % sensitivity and 100 % specificity; whereas, the cut-off value of uVDBP was 550 ng/mg with 96 % sensitivity and 84 % specificity. The findings of the present study suggest that uMCP-1 and uVDBP may be considered as novel potential diagnostic biomarkers for the early detection of diabetic nephropathy.