The fibrinolytic system in patients with diabetes mellitus with special reference to diabetic retinopathy.

The fibrinolytic system has been studied in 168 patients with diabetes mellitus (DM) and compared to that of a group of 153 sex- and age-matched control subjects. The following determination were made: spontaneous fibrinolytic activity of the blood; fibrinolytic response to standardized venous stasis (stimulated fibrinolytic activity, "fibrinolytic capacity"); histochemical determination of fibrinolytic activators in the walls of superficial veins collected by biopsy. Diabetic patients were found as a group to have an impaired fibrinolytic system with the above fibrinolytic parameters decreased to various degrees in comparison with those of the controls. Less clear differences were observed between patients with and without ophthalmoscopically visible diabetic changes of the retina. However, patients with beginning angiopathy were found to have a significantly higher amount of fibrinolytic activators in their vessel walls than patients with more advanced retinopathy and without ophthalmoscopically detectable retinopathy. Furthermore, unlike patients without retinopathy, patients with retinopathy increased less or did not increase at all their spontaneous and stimulated fibrinolytic activity along the duration of the disease. The defective fibrinolytic system of diabetic patients may contribute to the occurrence of the vascular complications frequently seen in this disease. In the diabetic group, those patients who develop retinopathy show an impaired fibrinolytic defense with the duration of the disease.