Levels of urinary matrix metalloproteinase-9 (MMP-9) and renal injuries in patients with type 2 diabetic nephropathy

To determine correlations among the levels of urinary MMP-9 and type-IV collagen, hyperglycemia, urinary protein excretion, and renal injuries in patients with type 2 diabetic nephropathy, we measured levels of urinary MMP-9 and protein, blood urea nitrogen (BUN), serum creatinine (s-Cr), fasting plasma glucose (FPG), and glycohemoglobin A1c (HbA1c) in 47 diabetic patients and 14 healthy adults. Urinary type-IV collagen was also measured in 28 diabetic patients and seven healthy adults. Patients with diabetic nephropathy were divided into two groups: 1). patients with normoalbuminuria or microalbuminuria (0-299 mg/g.Cr; n=27), and 2). patients with macroalbuminuria (>300 mg/g.Cr; n=20). The mean level of urinary MMP-9 in group 2 was significantly higher than those in healthy adults (P<0.05), and the levels of urinary MMP-9 in patients with diabetic nephropathy increased in accordance with the clinical stage of the disease. The levels of urinary MMP-9 tended to be correlated with HbA1c in these patients, but the correlation was not statistically significant. The mean level of urinary type-IV collagen in group 2 of patients with diabetic nephropathy was significantly higher than that in group 1 and healthy adults. Levels of urinary type-IV collagen in patients with diabetic nephropathy also increased in accordance with the clinical stage of the disease. The results suggest that measurements of urinary MMP-9, as well as urinary type-IV collagen, may be useful for evaluating the degree of renal injuries in patients with type 2 diabetic nephropathy, especially in the early stage.