Hormonal and substrate responses during recovery from hypoglycaemia in man during beta1‐selective and non‐selective beta‐adrenergic blockade

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Abstract
Recovery from acute hypoglycemia induced by the injection of insulin was examined in 6 human subjects under control conditions, under nonselective .beta. blockade (propranolol) and under selective .beta.1-blockade (metoprolol). The normal blood glucose recovery was biphasic with an initial rapid and a slower subsequent phase of recovery. The early recovery mechanism was unaffected by either form of .beta.-blockade, but with propranolol the late phase of recovery was significantly prolonged. Rises in blood lactate and plasma free fatty acids following hypoglycemia were markedly reduced by propranolol but to a much lesser degree with metoprolol. The counterregulatory hormonal responses of glucagon, cortisol and growth hormone were augmented appropriately for the prolonged hypoglycemia associated with propranolol. Non-selective .beta.-adrenergic blockade with propranolol is associated with an impairment of the late phase of blood recovery from hypoglycemia. The possible mechanism of this impairment are discussed.