Glucagon is used for the emergency treatment of severe hypoglycemia. Glucagon is only effective in patients with hypoglycemia if liver glycogen is available; the drug is of little or no value in patients with chronic hypoglycemia or in those with hypoglycemia associated with starvation or adrenal insufficiency. The increase in blood glucose concentration produced by glucagon is not as great in patients with type 1 diabetes mellitus as compared to those with type 2 diabetes mellitus; supplemental carbohydrate should be administered as soon as possible, especially to pediatric patients. The hyperglycemic response produced by glucagon may be reduced in emaciated or undernourished patients or in those with uremia or hepatic disease. Unlike IV dextrose, parenteral administration of glucagon results in a smooth, gradual termination of insulin coma. Glucagon is convenient for use in emergency situations when dextrose cannot be administered IV.
Depending on the stage of coma and the route of administration, patients usually become conscious within 5-20 minutes following parenteral administration of glucagon. After the patient responds, supplemental carbohydrate should be administered to restore liver glycogen and prevent secondary hypoglycemia. In patients in very deep coma, IV dextrose should be administered in addition to glucagon. If an unconscious diabetic patient suspected of being in insulin coma does not awaken following administration of glucagon, an additional dose of glucagon can be administered; emergency assistance should be sought. Other causes of coma should be considered. Failure of glucagon to relieve the coma may be caused by marked depletion of hepatic glycogen stores or irreversible brain damage resulting from prolonged hypoglycemia. In emergency situations in which hypoglycemia is suspected but not established, glucagon shouldnot be substituted for IV dextrose.
Radiographic Examination of the GI Tract
Glucagon is used as a diagnostic aid in the radiographic examination of the stomach, duodenum, small intestine, and colon when a hypotonic state would be advantageous. Glucagon appears to be as effective as antimuscarinics for this purpose and is associated with fewer adverse effects. Concomitant administration of glucagon and an antimuscarinic agent may result in increased adverse effects.
Glucagon has been used with some success as a cardiac stimulant for the management of cardiac manifestations (e.g., bradycardia, hypotension, myocardial depression) associated with severe β-adrenergic blocking agent overdosage or calcium-channel blocking agent overdosage. Glucagon has successfully reversed such manifestations in patients unresponsive to other drugs (e.g., atropine, epinephrine, dopamine, dobutamine), and should be administered early in the management of severe β-blocker overdosage. Experience in calcium-channel blocker overdosage is more limited, but glucagon (combined with inamrinone in at least one case) has been similarly effective in some patients.