Platelet reactivity in diabetic patients subjected to acute exercise stress test

Background: Previous studies have reported ambiguous results regarding the effect of acute exercise on platelet reactivity in healthy and cardiac patients. Objectives: We aimed to assess platelet reactivity among diabetic patients before and immediately after an acute exercise stress test. Methods: Patients (controls: mean age 53.1±12.1 years; four males; body mass index 27.0±5.7 kg/m²; HbA_1c 6.0±1.1%, n=8) and diabetic patients (52.9±11.3; six males; body mass index 30.7±2.2 kg/m²; HbA_1c 7.8±1.7%, n=8) referred for diagnostic nuclear exercise stress test were recruited. Blood samples obtained at rest and immediately post-exercise were stimulated with adenosine diphosphate (ADP), collagen and arachidonic acid. Expression of CD41 (pan-platelet marker) and CD62p (platelet stimulation marker) were measured by flow cytometry. Aspirin responsiveness was measured using VerifyNow. Results: Although peak systolic blood pressure was significantly higher in the diabetics compared with nondiabetics (186.3±25.4 vs. 157.1±19.1, respectively, P=.028), peak exercise heart rate was similar (156.5±8.3 vs. 155.5±12.1 for diabetics and nondiabetics, respectively). No differences were observed between groups for aspirin resistance. Platelet stimulation with ADP exhibited significantly lower CD62p-positive cell population (%) in the diabetic patients both prior to and following the exercise stress test (P=.03). In addition, although not significant, platelet stimulation was higher post-exercise in the diabetic patients (6.3±4.7% vs. 12.0±5.6%, for pre- and post-exercise, respectively, P=.2) with no difference in controls (9.2±5.5% vs. 8.9±5.9%). Conclusion: Platelet stimulation in diabetic patients is blunted and might be explained by the prolonged exposure of platelets to multiple diabetic risk factors.