Plasma and urine fibrinopeptide-A (FPA) levels were investigated in type I and II diabetic patients. Plasma FPA and 24-h urinary excretion of FPA were significantly elevated in diabetic patients compared with normal volunteers, indicating augmented thrombin activity in diabetes. Plasma and urine FPA did not differ between type I and type II diabetic subjects. Comparison ofplasma FPA with blood glucose and hemoglobin A1 (HbA,) indicated that elevation of FPAis rapidly reversible and intermittent during hypo- and hyperglycemia. Although elevated plasma FPA was seen in patients of short as well as long duration of diabetes, plasma and urine FPA correlated with duration of diabetes in type I patients.
In type I diabetic patients with vascular complications, hyperglycemia induced by an oral glucose challenge was accompanied by elevation of plasma FPA and acceleration of fibrinogen disappearance. These responses were not seen when the patients were treated with intravenous (i.v.) heparin before the glucose challenge. In patients without vascular complications, there was also an acceleration of fibrinogen disappearance and a marginal (not statistically significant) elevation of plasma FPA seen after the FPA response observed in vascular disease patients. In all patients, induced hyperglycemia resulted in a decrease in hematocrit and hemoglobin (blood volume expansion) and an increase in pulse pressure indicating hemodynamic changes. The association of hyperglycemia and hemodynamic changes with augmented thrombin activity is consistent with a mechanism for fibrin formation and deposition based on endothelial injury and/or increased vascular permeability. Fibrin deposition due to such a mechanism may participate in the development of the vascular complications of diabetes.