Serum concentrations of intact type IV collagen in diabetics

We developed a sandwich enzyme immunoassay for intact type IV collagen (IV-C) using two monoclonal antibodies as a marker of basement membrane metabolism, and examined the relationship between serum IV-C and diabetic complications. Serum IV-C was measured in 186 diabetics with or without clinical signs of retinopathy, neuropathy, and/or nephropathy, and 328 healthy subjects. Serum IV-C was significantly (P < .01) higher in diabetics (mean ± SE: 124.83 ± 2.94 ng/ml) than in healthy subjects (73.32 ± 1.42 ng/ml). In diabetics with microangiopathy, serum IV-C became higher as clinical signs worsened. Especially in diabetics with nephropathy, serum IV-C became higher with the elevation of blood urea nitrogen (BUN), serum creatinine, and β₂-microglobulin. Serum IV-C level seems to be a useful marker for assessment of the activity or progression of diabetic microangiopathy, and for evaluation of therapeutic effects.