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The role of epinephrine in platelet activation and the effect of an alpha 2-adrenoceptor antagonist, midaglizole, during insulin-induced hypoglycaemia in Type 2 (non-insulin-dependent) diabetes mellitus were examined. The action of midaglizole as a platelet alpha 2-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 alpha 2-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 less than 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 beta-thromboglobulin was increased at the hypoglycaemic nadir (165.5 +/- 12.6 ng/ml) compared with the level at 0 min (121.0 +/- 11.5, p less than 0.005) in the control group, whereas no significant increase was demonstrated in the alpha 2-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 alpha 2-adrenoceptor antagonist.

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Nine non-diabetic,. non-obese, normocholesterolemic normal male subjects with varied triglycerides levels were subjected to a simultaneous infusion test with a synthetic somatostatin analogue [des(Ala', Gly2)-D-Trp8, D-Asn3,14-somatostatin], insulin and glucose under ambulatory conditions. The levels of Cpeptide reactivity, immunoreactive glucagon and growth hormone were reduced, and the level of immunoreactive insulin remained constant during the infusion. The blood glucose reached a constant value at 110-120 minutes (steady state blood glucose, SSBG) after the commencement of the infusion. The total cholesterol (TC) levels decreased slightly in the 30 minutes after the experiments were begun, and the triglycerides (TG) levels decreased gradually throughout the infusion period, due mainly to the reduction of very low density lipoprotein (VLDL). The most striking finding was the highly significant positive correlation (p<0.005, r=0.868) between SSBG and the serum TG level prior to the infusion.These results indicate an important relationship between insulin sensitivity and serum TG level. High TG level may be regarded as one of the indices of insulin resistance.