ANTIDIABETICS AND BETA BLOCKERS
In diabetics using insulin, the normal rise in blood sugar in response to hypoglycaemia may be impaired by propranolol, but serious and severe hypoglycaemia (sometimes accompanied by an increase in blood pressure) seems rare. Other beta blockers normally interact to a lesser extent or not at all. The blood glucose lowering effects of sulphonylureas may possibly be reduced by beta blockers. Be aware that in the presence of beta blockers some of the familiar warning signs of hypoglycaemia may not occur. (19)
Monitor the effects of concurrent use well, avoid the non-selective beta blockers
where possible, and check for any evidence that the dosage of the antidiabetic needs some adjustment. Warn all patients that some of the normal premonitory signs of a hypoglycaemic attack may not appear, in particular tachycardia and tremors, whereas the hunger, irritability and nausea signs may be unaffected, and sweating may even be increased.