Effect of α 2 -adrenoceptor antagonist on platelet activation during insulin-induced hypoglycaemia in Type 2 (non-insulin-dependent) diabetes mellitus

The role of epinephrine in platelet activation and the effect of an α2-adrenoceptor antagonist, midaglizole, during insulin-induced hypoglycaemia in Type 2 (noninsulin-dependent) diabetes mellitus were examined. The action of midaglizole as a platelet α2-antagonist was confirmed by in vitro studies using platelet-rich plasma and washed platelet suspension. Hypoglycaemia was induced by a bolus injection of short-acting insulin in 24 diabetic patients. They were divided into two groups, a control group (n=12) and an α2-group (n=12), and midaglizole was administered orally 60 min before insulin injection in the latter. Blood glucose and plasma C-peptide levels were significantly decreased (p<0.005) by insulin injection in both groups. Counter-regulatory hormones, including epinephrine, and arginine vasopressin were similarly increased at the hypoglycaemic nadir compared with the levels at 0 min in both groups. Plasma β-thromboglobulin was increased at the hypoglycaemic nadir (165.5±12.6ng/ml) compared with the level at 0 min (121.0±11.5, p<0.005) in the control group, whereas no significant increase was demonstrated in the α2 group. These results suggest that plasma epinephrine plays an important role in platelet activation during hypoglycaemia in Type 2 diabetes mellitus, and that the platelet activation is prevented by α2-adrenoceptor antagonist.