What it is
Glucagon is a 29-amino-acid peptide hormone made by the alpha cells of the pancreas. Its job is the opposite of insulin's: when blood sugar falls, glucagon tells the liver to break down glycogen — its store of sugar — and release glucose into the blood.
The glucagon used as a medicine is identical to the human hormone. Its sequence is:
HSQGTFTSDYSKYLDSRRAQDFVQWLMNT
The Baqsimi and Gvoke labels give the same molecular formula (C₁₅₃H₂₂₅N₄₃O₄₉S) and molecular weight (3,483). Gvoke's label adds that its glucagon is made by solid-phase chemical synthesis — built one amino acid at a time rather than extracted or grown.
How it works — and when it cannot
Glucagon binds to glucagon receptors in the liver and releases stored sugar. The labels are blunt about the limit: liver glycogen stores are necessary for it to work. Glucagon does not create sugar from nothing; it opens a store. The Baqsimi label names starvation, adrenal insufficiency and chronic low blood sugar as states in which the store may be too small.
The same action explains its two contraindications:
- Pheochromocytoma — glucagon may stimulate the tumour to release catecholamines (adrenaline-type hormones), with a substantial rise in blood pressure;
- Insulinoma — after an initial rise in blood sugar, glucagon may stimulate exaggerated insulin release from the tumour and cause low blood sugar.
The forms it comes in
Traditional rescue kits hold a powder and a liquid to be mixed at the time of use. Since 2019 two alternatives have been approved:
| Product | Form | Ages on the label | Half-life on the label |
|---|---|---|---|
| Glucagon kits (several makers) | Powder mixed with liquid, injected | varies by product | — |
| Baqsimi (2019) | 3 mg dry powder, sprayed into the nose | 1 year and over | ~35 minutes |
| Gvoke (2019) | Ready-to-use liquid, 1 mg in 0.2 mL | 2 years and over | 32 minutes |
| Zegalogue — dasiglucagon | Ready-to-use analogue, injected | 6 years and over | ~30 minutes |
Baqsimi's label notes that a common cold with nasal congestion, or a decongestant, did not change absorption — the obvious worry with a nasal rescue drug. Peak blood levels arrive around 15 minutes after the spray.
Dasiglucagon is not glucagon. It is a separate 29-amino-acid analogue (molecular mass 3,382, against 3,483 for glucagon), and its label is a separate approval.
A second, quieter use
Given into a vein, glucagon relaxes the smooth muscle of the gut and stops it moving for a short time. The GVOKE VialDx label is approved for exactly that: a diagnostic aid during radiologic examinations in adults. It is the one approved use of glucagon that has nothing to do with blood sugar.
The GLP-1 connection
The best-selling peptide drugs of the decade are named after this hormone. GLP-1 means glucagon-like peptide-1, and the likeness is measurable: laid side by side, glucagon and GLP-1(7-37) have the same amino acid at 14 of the first 29 positions — a count this library made from the two sequences. They act on different receptors and push blood sugar in opposite directions. Several newer weight-loss candidates, including retatrutide, survodutide and mazdutide, are built to act on both receptors at once.
Where it stands
Approved in the United States in several forms, from generic kits to the 2019 nasal and ready-to-use products. PubMed indexes 67,872 records for glucagon and 3,575 tagged as randomised controlled trials (2026-09-24); most of that literature studies the hormone itself — its role in diabetes and metabolism — rather than the rescue medicine.
Related reading
Liraglutide and semaglutide are the GLP-1 drugs whose hormone was named for glucagon. C-peptide is another peptide the pancreas releases, cut from insulin's precursor. For why most peptide hormones are injected or sprayed rather than swallowed, see the desmopressin entry, a peptide that still works as a tablet.