Effects of beta-blocking agents on insulin secretion and glucose disposal

Non-selective and to a lesser extent selective beta-blockers are known to slightly deteriorate glucose metabolism. This may be of clinical relevance, since patients with essential hypertension suffer from reduced insulin-sensitivity and some studies showed an increased incidence of diabetes type II with beta-blocker-treated hypertensive patients. However, it is not clear whether this effect is due to hypertension per se or in addition by antihypertensive treatment. The possible mechanisms by which beta-blockers influence carbohydrate metabolism are discussed. Insulin secretion is inhibited by beta-blockers in vitro. However, no effect is seen in vivo in man. Hepatic glucose production in theory may be influenced, but no effect is demonstrable. Muscular glucose uptake could be reduced; some data exist showing reduced peripheral insulin sensitivity, although there are controversial results. In conclusion, a deterioration of carbohydrate metabolism by beta-blockers is established, the mechanism whereby remains obscure.