Effect of Metoprolol and Alprenolol on the Metabolic, Hormonal, and Haemodynamic Response to Insulin‐Induced Hypoglycaemia in Hypertensive, Insulin‐Dependent Diabetics

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Abstract
Insulin hypoglycaemia was induced three times in 6 insulin‐dependent, hypertensive diabetics: before instituting antihypertensive long‐term treatment and after obtaining a satisfactory blood pressure with either alprenolol or metoprolol given in a randomized order. The blood glucose concentration (1.6–1.9 mmol/1) at which the hypoglycaemia necessitated intravenous administration of glucose was almost identical on all three occasions. During hypoglycaemia the systolic and diastolic blood pressures increased significantly by a mean maximal rise of 27/14 mmHg on alprenolol treatment, but remained unchanged on metoprolol. The responses of adrenaline, noradrenaline, cortisol, and growth hormone did not differ significantly on the three occasions. None of the β‐adrenergic drugs counteracted the early hormone defence mechanisms in hypoglycaemia and the signs of hypoglycaemia were not masked. The haemodynamic response was altered only by the non‐selective (alprenolol) and not by the selective β‐adrenergic blocking agent (metoprolol).