Hypertensive crisis caused by hypoglycemia and propranolol

In a patient with severe hypertension in association with insulin-induced hypoglycemia and prior therapy with propranolol hydrochloride, intravenous 50% dextrose significantly reduced arterial pressure on two occasions. Subsequent reduction of arterial pressure was observed with prazosin hydrochloride, an alpha-receptor antagonist. The hypertensive episode may have been caused by hypoglycemia stimulating excessive release of epinephrine. In the presence of vascular beta 2-receptor blockade by propranolol, the hypertensive action of epinephrine was mediated by vascular alpha-receptors. When beta-antagonists must be used in insulin-dependent diabetic patients, beta 1-selective antagonists appear to be a better choice.