Glucagon is a 29-amino-acid peptide hormone made by the alpha cells of the pancreatic islets. It is the counterweight to insulin. When blood sugar drops, glucagon rises, and the two hormones together keep glucose in a workable range. It is cut from a larger precursor protein, proglucagon, by the enzyme prohormone convertase 2 (Endotext / NCBI).
Unlike most compounds catalogued on this site, glucagon is not an obscure research peptide. It is a hormone your own body makes, and it has been an approved drug for more than sixty years.
What it does in the body
Glucagon binds G-protein-coupled glucagon receptors, concentrated in the liver. That binding activates adenylate cyclase, which raises intracellular cyclic AMP (cAMP). The rise in cAMP drives two processes: glycogenolysis, the breakdown of stored liver glycogen into glucose, and gluconeogenesis, the making of new glucose from amino acids and other precursors. The net effect is more glucose released into the blood. Glucagon also relaxes gastrointestinal smooth muscle through the same pathway (StatPearls / NCBI).
Secretion is tuned by the body. Low blood sugar, certain amino acids, and the gut hormone GIP push glucagon up; high blood sugar and GLP-1 push it down.
As a medicine
Eli Lilly's glucagon ampoule was first approved by the FDA in 1961 for severe hypoglycemia. It remains the standard rescue treatment for a dangerous low when a person cannot safely swallow sugar or has lost consciousness, and it is especially useful when there is no IV access (StatPearls / NCBI).
The drug also has a second, less familiar use: because it relaxes the gut, it is given as a diagnostic aid to reduce bowel motility during imaging and endoscopy.
For decades the only option was a freeze-dried powder that a caregiver had to reconstitute and inject during an emergency, which is hard to do well under stress. Newer formulations removed that step:
- Baqsimi, a 3 mg nasal powder from Eli Lilly, was approved in July 2019 as the first needle-free, ready-to-use glucagon. In testing, caregivers administered it far faster than a traditional injection kit (Eli Lilly investor release).
- Gvoke (Xeris), a ready-to-inject pen and prefilled syringe, was approved in September 2019.
- Zegalogue (dasiglucagon, Zealand Pharma) was approved in 2021. It is a glucagon analog, not native glucagon: seven of the 29 amino acids are swapped to keep the peptide stable in a premixed liquid solution (Zegalogue FDA label).
Common adverse effects include nausea, which is frequent. Glucagon is contraindicated in people with pheochromocytoma or insulinoma, among others (StatPearls / NCBI).
Where the research is going
The glucagon receptor is now a drug target in its own right, beyond emergency use. The current direction is combination molecules. Survodutide, a single peptide that activates both the glucagon and GLP-1 receptors, reported an average weight loss of about 16.6% over 76 weeks in a Phase 3 obesity trial, with gastrointestinal side effects the most common issue (Boehringer Ingelheim). The idea is that GLP-1 reduces appetite while glucagon-receptor activity acts on the liver and energy expenditure. These dual agonists are investigational and not the same product as the rescue glucagon described above.
Quality and sourcing notes
Prescription glucagon products (Baqsimi, Gvoke, Zegalogue, generic injectable glucagon) are FDA-approved medicines dispensed through pharmacies with manufacturer quality control. They are not research chemicals.
That distinction matters. "Glucagon" sold as a research-use-only powder by peptide vendors is a different supply chain with no regulatory oversight of identity or purity. A 29-amino-acid peptide is non-trivial to synthesize cleanly, and a certificate of analysis (COA) showing mass-spec identity and HPLC purity from an independent lab is the minimum a careful buyer would want. peptideone aggregates third-party COAs and vendor reputation signals; it sells nothing and runs no tests of its own.
Nothing here is medical or dosing advice. Severe hypoglycemia is a medical emergency, and approved glucagon rescue products should be used only as directed by a clinician.