Nursing care
Glucagon: what to check before you give it
Written and reviewed by Dana Whitfield, RN, MSN · 5 min read · Updated September 2026
Short answer
Glucagon raises blood glucose by triggering the liver to release stored glycogen, and it is the go-to rescue drug for the unconscious or seizing hypoglycaemic patient who cannot safely swallow oral glucose. Give it, then position the patient on their side, because vomiting is a near-certain side effect on waking.
Mechanism, simply
Glucagon is a pancreatic hormone that opposes insulin. It binds hepatic receptors and stimulates glycogenolysis, breaking down stored glycogen into glucose that the liver releases into the bloodstream. In sustained hypoglycaemia it also promotes gluconeogenesis, though the immediate rescue effect comes almost entirely from glycogen breakdown.
Because the mechanism depends on liver glycogen stores, the response fails in patients who have none to draw on — someone who is malnourished, has been fasting for days, or has advanced liver disease will not respond to glucagon the way a well-nourished patient will. That is why oral or IV glucose is still needed as a follow-up once the patient can safely receive it.
Indications you will see on the ward
The primary use is severe hypoglycaemia in a patient too obtunded, combative, or seizing to take anything by mouth, most often an insulin-dependent diabetic. Family members and school staff are also taught to give it via auto-injector or nasal spray for exactly this scenario outside hospital.
In a different setting entirely, glucagon is used in endoscopy and radiology to relax smooth muscle — it slows GI motility enough to improve imaging of the bowel during procedures like barium studies or ERCP. It also has a niche role as a reversal agent in beta-blocker or calcium channel blocker overdose, where its inotropic effect bypasses the blocked receptor.
Assessment before administration
Confirm hypoglycaemia with a fingerstick glucose before giving glucagon if time allows, though in an unresponsive patient with known diabetes, treatment should not wait for confirmation. Check the route being used — IM, subcutaneous, or the newer nasal spray formulation — and confirm the correct reconstitution if using the injectable kit, since it must be mixed immediately before use and not stored once prepared.
Assess airway and level of consciousness, and have the patient positioned to protect against aspiration before the injection, since vomiting on waking is expected rather than an adverse surprise. Ask about alcohol use and recent food intake if possible; a patient with depleted glycogen stores from starvation or heavy alcohol use may not respond adequately and will need IV dextrose instead.
Toxicity and the antidote
Glucagon has no specific antidote and true toxicity is rare because the therapeutic dose window is narrow and self-limiting — excess simply raises glucose further, which is managed with insulin if it becomes clinically significant. The more common problem after administration is not overdose but non-response, when hepatic glycogen stores are exhausted and blood glucose fails to rise.
Watch for nausea and vomiting in nearly every patient who receives it, which is expected rather than a sign of adverse reaction. Rebound hypoglycaemia can follow thirty to sixty minutes after the initial rise, once the mobilised glycogen is used up, so recheck blood glucose on a schedule and follow with oral carbohydrate as soon as the patient is alert enough to swallow safely.
Interactions that matter
Glucagon's effect depends on intact liver glycogen, so it is markedly less effective in patients who are chronically malnourished, fasting, or have significant hepatic disease — IV dextrose is the more reliable choice in those patients regardless of what a protocol suggests.
In beta-blocker overdose, glucagon is given deliberately alongside the patient's other cardiac medications because its inotropic effect works through a pathway the beta-blockade does not touch. It can also transiently inhibit insulin secretion, which is clinically irrelevant in the acute hypoglycaemic setting but worth knowing when glucagon is used for its GI-relaxant effect during a procedure.
What the patient must be told
Anyone at risk of severe hypoglycaemia should have a glucagon kit at home, and a family member, roommate, or coworker should know how and when to use it — the patient themselves will likely be unconscious when it is needed. Teach them to lay the person on their side immediately after the injection, because vomiting is expected as the patient regains consciousness, and this position protects the airway.
Explain that glucagon is a rescue measure, not a substitute for calling for emergency help — if the person does not respond within ten to fifteen minutes, or does not wake fully, emergency services should be contacted. Once alert, the patient needs to eat a carbohydrate-containing snack or meal promptly to prevent the glucose level dropping again as the glucagon effect wears off.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our endocrine practice questions are the closest set to what this page covers.
Common questions
Why position the patient on their side after giving glucagon?
Because nausea and vomiting are an expected effect as the patient regains consciousness, not a rare complication. Side-lying protects the airway from aspiration while they are still groggy and cannot reliably manage their own secretions.
Why doesn't glucagon work in every hypoglycaemic patient?
It works by releasing glucose from stored liver glycogen, so it fails when those stores are depleted — in prolonged fasting, malnutrition, chronic alcohol use, or significant liver disease. Those patients need IV dextrose instead.
Can glucagon be given if you're not sure the patient is hypoglycaemic?
In an unresponsive known diabetic where fingerstick testing isn't immediately possible, treating presumptively is standard, since untreated severe hypoglycaemia causes permanent harm faster than a mistaken dose of glucagon does. Confirm with a glucose check as soon as it's practical.
Does glucagon replace oral glucose or IV dextrose?
No. It buys time by mobilising a short-lived glucose supply. Once the patient is alert enough to swallow safely, they still need oral carbohydrate, and rebound hypoglycaemia should be anticipated and rechecked for over the following hour.
Why is glucagon used in beta-blocker overdose?
Because it raises heart rate and contractility through a receptor pathway independent of the beta receptor that the overdose has blocked, making it one of the few agents that can restore cardiac output when standard inotropes fail to work through the blocked pathway.