Both recognition and prevention of drug-induced hypoglycemia require awareness of the clinical conditions favoring its occurrence and the drugs and drug combinations most likely to cause it. Restricted food intake, age, hepatic disease and renal disease are the main predisposing factors, individually and even more so in combination. Everyone in general, and insulin-requiring diabetics in particular, should always eat carbohydrate whenever they drink alcohol. Sulfonylurea hypoglycemia has been reported often in diabetics older than fifty years, with more cases treated with chlorpropamide being reported than cases treated with other sulfonylureas ; it should therefore be used warily in older patients, and only when they are under daily observation by family or friends. In elderly diabetics taking any sulfonylurea agent, warfarin should be used for anticoagulation instead of bishydroxycoumarin, indomethacin for arthritic pain instead of phenylbutazone, and another agent than sulfisoxazole for urinary tract infections. Also in elderly diabetics using sulfonylureas, therapeutic doses of salicylates, monoamine-oxidase inhibitors and probably pro-pranolol should be co-administered with caution, including frequent blood glucose monitoring as long as necessary. Finally, the danger of refractory hypoglycemia in the newborn .proscribes the mother's use of sulfonylureas during the last month of pregnancy. Drug-induced hypoglycemia is now so relatively common that virtually every unconscious patient should be considered hypoglycemie until immediate estimation of the blood sugar level rules the condition in or out. If it is ruled in, the clinician should promptly start 10 per cent glucose by vein and plan to maintain it uninterruptedly for one or more days, with added hydrocortisone and glucagon if necessary, until persistent hyperglycemia guarantees that all drug effects have worn off.