Abstract
1 The effect of acebutolol, a relatively selective beta-adrenoceptor blocking drug and propranolol, a non-selective one, on the hypoglycaemic action of glibenclamide after an oral glucose load has been investigated in a group of maturity-onset diabetic patients. 2 Glibenclamide significantly reduced the blood glucose levels and both acebutolol and propranolol, at therapeutic doses, were found to modify this action significantly. 3 The effect of acebutolol was slightly less than that of propranolol. The difference was not statistically significant. 4 The modes of action of sulphonylureas are reviewed and it is suggested that beta-adrenoceptor blockers may modify their effect on insulin release. This appears to be a drug interaction rather than an effect of beta-adrenoceptor blockade on glucose tolerance.