The basement membranes of the glomerular capillaries thicken in diabetic nephropathy, which can obliterate the blood vessels. The mesangial cells that surround the glomerular vessels increase due to deposits of similar material to the basement membrane. This results in diffuse glomerulosclerosis in 50% of cases, accompanied by nodular sclerosis known as Kimmelstiel-Wilson nodules, which are pathognomonic of diabetes. The loss of heparan sulfate in the basement membrane allows increased filtration of albumin, leading to microalbuminuria and diabetic nephropathy.