Recent findings in atrial fibrillation (AF) patients receiving oral anticoagulation showed that diabetes without insulin therapy has a thromboembolic risk comparable to nondiabetic patients, whereas only diabetic patients on insulin have a heightened thromboembolic risk. We explored possible pathophysiological correlates of such finding on 90 AF patients on oral anticoagulation, divided according to diabetes status (n = 30 without diabetes; n = 29 with diabetes on oral antidiabetic drugs; n = 31 with insulin-requiring diabetes). We assessed von Willebrand Factor (VWF) concentration (VWF:Ag) and activity (VWF R:Co) as measures of endothelial dysfunction; and thrombin-activatable fibrinolysis inhibitor (TAFI) and prothrombin fragment 1 + 2 (F1+2) levels as markers of fibrinolytic activity and thrombin generation. Values of VWF:Ag, VWF:RCo, and TAFI were similar in the 3 groups. Patients with diabetes requiring insulin had significantly higher levels of F1+2 (median 23.1 pg/ml [interquartile range 17.6; 33.5]) than those without diabetes (16.3 pg/ml [11.5; 22.5], p = 0.036) and diabetic patients on oral antidiabetic drugs (20.6 pg/ml [13.3; 29], p = 0.046). Thus, in AF patients receiving oral anticoagulation, those with diabetes, regardless of the diabetes type (with or without insulin therapy), and those without diabetes have comparable indices of the explored parameters of endothelial dysfunction and fibrinolytic activity. Despite anticoagulant therapy, thrombin generation is selectively higher in diabetic patients' on insulin than in those without diabetes or with diabetes on oral antidiabetic drugs, with no differences between these latter 2 conditions. Thrombin generation might thus be a predominant contributor to the excess of thromboembolic risk in AF patients on insulin-requiring diabetes.
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