Changes of human glomerular basement membrane in diabetes mellitus

Glomerular basement membranes were isolated from kidneys of human diabetics and non-diabetics. Albumin and immunoglobulin G content of glomerular basement membranes as determined after protease digest was higher in the diabetic group while lower values were obtained for heparan sulphate. Nonenzymatic glucosylation of whole glomerular basement membranes and tendon tissue was significantly elevated in diabetic subjects. Correlation of the determined parameters suggest that charge and size selective properties are altered in diabetic glomeruli. Serum albumin and albumin deposited in glomerular basement membranes showed the same content of nonenzymatically bound glucose in a normal and in a diabetic subject, respectively. Thus it would appear that in human diabetes the glucosylated albumin does not underly increased transcapillary transport as was reported in vitro.