Collagen binding activity in sera of patients with insulin-dependent (type 1) and non insulin-dependent (type 2) diabetes mellitus.

An increase in the capacity of serum IgG to bind to native type IV collagen was observed in patients with both insulin-dependent and non insulin-dependent diabetes mellitus. This increased binding seems to be due to circulating immune complexes in the majority of the cases and to autoantibodies in some. The increased collagen binding activity was associated in postpubertal patients with the presence of diabetic microangiopathy, suggesting a pathogenetic role.