[The significance of determination of urinary type IV collagen concentrations from a random urine collection in patients with non-insulin dependent diabetes mellitus].

Recently, we have developed a highly sensitive assay system for quantitative measurement of urinary type IV collagen. To obtain a basic evaluation of the assay system we used urine specimens, collected randomly and studied the relation to diabetic nephropathy in patients with non-insulin dependent diabetes mellitus (NIDDM). It was shown that this assay system could measure the samples without concentrating the urine. Urinary sediments which were reported to interfere with the assay could be removed by adding Tris-buffer. In the clinical studies, urinary type IV collagen concentrations were significantly higher in patients with NIDDM regardless of the presence or the absence of albumin. Cases with abnormal values of urinary type IV collagen in the normal albuminuria group were 41.6%, while those with abnormal values of urinary transferrin excretion were 31.0%. Furthermore, among the normal albuminuria group, glycosylated hemoglobin (HbA1c) levels were higher in the groups of abnormal values of urinary type IV collagen than those within the reference values. These results obtained herein suggest that urinary type IV collagen could be a useful marker for the early stage of diabetic nephropathy.