Moderate Exercise Increases Platelet Function in Type I Diabetic Patients Without Severe Angiopathy and in Good Control

Abstract

OBJECTIVE The aim of this study was to investigate whether a 45-min moderate exercise, performed postprandially with a timing that partially prevented the risk of hypoglycemia, was able to modify platelet function in patients affected by insulin-dependent (type I) diabetes mellitus without severe late complications and in a good metabolic control. RESEARCH DESIGN AND METHODS We submitted 6 male type I diabetic patients (27.2 ± 3.4 yr; body mass index, 21.4 ± 0.6 kg/m2; HbA1c, 7.6 ± 0.9%) on a daily three-insulin injection regimen, without severe late complications of diabetes, to a 45-min moderate exercise (about 50% of maximal oxygen consumption) with a cycle ergometer, beginning 180 min after breakfast and 195 min after a subcutaneous shot of regular insulin. Serial venous blood samples were conducted to measure plasma glucose, free insulin, counterregulatory hormones (glucagon, growth hormone, cortisol, and catecholamines), platelet sensitivity to ADP, platelet activating factor and collagen, and plasma concentrations of the platelet-specific protein beta-thromboglobulin (a marker of the platelet release reaction in vivo). RESULTS Exercise was accompanied by a decrease of plasma glucose (from 5.9 ± 1.2 to 4.6 ± 1 mmol/L, P = 0.067) and free insulin (from 180 ± 36 to 114 ± 30 pmol/L, P = 0.003), and by a significant increase of growth hormone (from 5 ± 1 to 15 ± 4 μg/L, P = 0.045), cortisol (from 240 ± 30 to 406 ± 69 nmol/L, P = 0.018), epinephrine (from 1005 ± 240 to 5143 ± 1753 pmol/L, P = 0.077), and norepinephrine (from 5.04 ± 1.08 to 13.48 ± 2.98 nmol/L, P = 0.009). Platelet sensitivity to the agonists and plasma concentrations of β-thromboglobulin increased during the exercise period. In particular, ADP ED50 reached during exercise 61 ± 16% of basal values (P = 0.048), platelet activating factor ED50 reached 73 ± 11% (P = 0.043), and collagen ED50 reached 68 ± 9% (P = 0.008). β-Thromboglobulin rose from 24 ± 2 to 32 ± 3 μg/L (P = 0.007). CONCLUSIONS Moderate exercise enhances platelet function in type I diabetic patients without severe angiopathy and in a good metabolic control.