Circulating tissue-type plasminogen activator and plasminogen activator inhibitor type 1 in proliferative diabetic retinopathy: a pilot study

Several haemostatic abnormalities are associated with proliferative diabeti c retinopathy. While abnormalities in plasma fibrinolytic activity have bee n described in diabetic retinopathy, platelets (a rich source of plasminoge n activator inhibitor type 1, PAI-1) have received little attention. As a r esult, little is known about the fibrinolytic potential of circulating whol e blood in diabetic retinopathy. The concentrations trations of tissue-type plasminogen activator (t-PA) and of its fast-acting inhibitor, PAI-1 were measured in plasma from eight patients with type 1 diabetes complicated by proliferative retinopathy, and from eight patients with type 1 diabetes and background or no retinopathy, matched for age, sex and duration of diabete s. The concentration of PAI-1 in platelets was also measured. The ratio of t-PA to PAI-1 in plasma was significantly higher in patients with prolifera tive retinopathy than in those without (0.66 vs. 0.37, p < 0.02). The avera ge quantity of PAI-1 per platelet was significantly lower in the group with proliferative retinopathy (0.33 vs. 0.50 ng/10(6) platelets, p < 0.02). Th ese data suggest that among patients with type 1 diabetes, total circulatin g fibrinolytic potential is higher in those with proliferative retinopathy.