Summary
The fibrinolytic system was studied in 96 patients with type I diabetes mellitus.
Patients were grouped according to their degree of retinopathy; 38 patients with no
evidence of retinopathy, 28 patients with background retinopathy and 30 patients with
proliferative retinopathy. Thirty healthy individuals served as controls. The basal
fibrinolytic activity as measured by clot lysis time and t-PA activity was increased
in diabetic patients. This was associated with low levels of plasminogen activator
inhibitor. Increased levels of D-dimer in diabetic patients further indicate enhanced
in vivo fibrinolysis. The increase in fibrinolytic activity was highest in diabetics
without retinopathy, and decreased with increasing retinopathy. Endothelial release
of t-PA after venous occlusion was not different between controls and all diabetic
groups. These findings suggest that in type I diabetics the fibrinolytic system is
in an activated state. With worsening of retinopathy this increase in fibrinolytic
activity diminishes.
