Beta-and alpha-adrenergic blockade and metabolic responses to insulin induced hypoglycaemia in diabetics.

: The metabolic, autonomic and symptomatic effects of labetalol and metoprolol in comparison with placebo, were studied during insulin induced hypoglycaemia in 5 non-insulin dependent diabetics. Both drugs suppressed the expected increase in heart rate during hypoglycaemia, but did not affect awareness of hypoglycaemic symptoms. Neither drug produced a rise in blood pressure during hypoglycaemia nor delayed the recovery from insulin-induced hypoglycaemia. In both there was no inhibition of release of gluconeogenic substrates such as free fatty acids. The results indicate that both metoprolol, a selective beta-blocker, and labetalol, a combined alpha beta-blocker, do not impair awareness of hypoglycaemia nor alter the metabolic response to hypoglycaemia in diabetics.