Glucagon

Glucagon is an emergency antihypoglycemic medication. It raises blood glucose by signaling the liver to release glucose from stored glycogen and to produce additional glucose through gluconeogenesis. This mechanism explains both its value and its limitation. Glucagon cannot release glycogen that is no longer there. Its effect may be weak or absent in starvation, prolonged fasting, advanced liver disease, adrenal insufficiency, chronic or recurrent hypoglycemia, significant recent alcohol intake, or a very low-carbohydrate diet. In these settings, oral glucose is preferred if swallowing is safe; otherwise, IV dextrose is the more reliable rescue treatment. Glucagon treats the immediate low glucose state. It does not correct the cause of the episode, such as excessive insulin, a missed meal, unexpected exercise, alcohol use, or a sulfonylurea dose that continues lowering glucose after the initial rescue.