Diabetic retinopathy and the fibrinolytic system.

We found that patients with long-standing (greater than 10 years) diabetes who have not developed retinopathy had a significantly higher and almost normal fibrinolytic response to venous occlusion and also a higher spontaneous fibrinolytic activity than those who had developed retinopathy. In the latter, the low fibrinolytic activity of the blood was, however, not correlated to a low plasminogen activator activity of the vessel walls. Although generally lower than in controls, the activator activity of the vessel walls in the retinopathy group tended to be higher than in the rest, and in fact those with only minor vascular changes (microaneurysms) had a significantly higher activity than the other diabetics. The fibrinogen and alpha2-macroglobulin levels were higher in the retinopathy group. Thus multiple abnormalities of the fibrinolytic system were found to be related to diabetic microangiopathy.