Abstract
Capillary basement membrane thickening in diabetes mellitus is generally first observed in the early stages of microangiopathy. For this reason, we measured type IV collagen (IV-7S), laminin (lam), and type III procollagen peptide (P-III-P) in sera and urine by RIA in 23diabetic patients with and without microangiopathy and in patients with other diseases, such as chronic glomerulonephritis (n=13), nephrotic syndrome (n=8), collagen diseases (n=12), and liver cirrhosis (n=5). There were significant elevations in serum levels of IV-7S, lam and P-III-P in association with the severity of diabetic retinopathy and/or nephropathy, even in the early stage of both diabetic microangiopathies. There were also elevations of urinary IV-7S and lam associated with the severity of diabetic nephropathy, in contrast to the other diseases. In conclusion, determination of serum or urinary levels of basement membrane components, i. e., IV-7S, lam and P-III-P, could be helpful as early indicators of diabetic microangiopathy, including diabetic nephropathy, and may also facilitate the differential diagnosis of diabetic nephropathy from other renal diseases.
