Diabetics receiving insulin, oral
antidiabetics, or diet alone need not abstain from
alcohol, but they should drink only in moderation and accompanied by food.
Alcohol makes the signs of hypoglycaemia less clear, and delayed hypoglycaemia can occur.
The
CNS depressant effects of
alcohol in association with hypoglycaemia can make driving or the operation of dangerous machinery much more hazardous. Metformin does not carry the same risk of lactic acidosis seen with phenformin and it is suggested by the British Diabetic Association that one or two drinks a day are unlikely to be harmful to those taking
metformin. A flushing reaction is common in patients taking
chlorpropamide who drink
alcohol, but is rare with other sulphonylureas.
Diabetics are advised not to exceed 2 drinks (for women) or 3 drinks (for men) daily and limit the intake of drinks with high-carbohydrate content (e.g. sweet sherries, liqueurs). Diabetics should not drink on an empty stomach and they should know that the warning signs of hypoglycaemia may possibly be obscured by the effects of the
alcohol and that the hypoglycaemic effects of
alcohol may occur several hours after drinking. The chlorpropamide-alcohol interaction (flushing reaction) is very well documented, but of minimal importance. It is a nuisance and possibly socially embarrassing but normally requires no treatment. Patients should be warned.