Glucagon
Metabolic / EmergencyAlso known as: GlucaGen, Baqsimi, Gvoke
Mechanism
The body's natural "blood sugar rescue" hormone, produced by pancreatic alpha cells. Pharmaceutical glucagon is used as an emergency treatment when a diabetic person's blood sugar drops dangerously low (severe hypoglycemia). Now available in easier-to-use forms: a nasal powder (Baqsimi) that a bystander can puff into the nose, and an auto-injector (Gvoke) that works like an EpiPen.
Technical detail
Recombinant or synthetic 29-amino acid peptide identical to endogenous glucagon produced by pancreatic alpha cells. Activates glucagon receptor (GCGR), a class B GPCR on hepatocytes. Gs/cAMP/PKA signaling activates glycogen phosphorylase (glycogenolysis) and upregulates PEPCK/G6Pase (gluconeogenesis), rapidly increasing hepatic glucose output. Also stimulates lipolysis in adipose tissue and has positive inotropic/chronotropic cardiac effects via cardiac GCGR. Hypoglycemia rescue: 1 mg IM/SC/IV (adults), onset 8-10 min (IM), peak ~13 min. Baqsimi: 3 mg intranasal powder (bioavailability ~25-50%), onset ~10-15 min. Gvoke: 0.5-1 mg SC auto-injector/pre-filled syringe (dasiglucagon, a stable analog, is a separate product). Also used as GI motility inhibitor for radiological procedures (0.25-0.5 mg IV). Requires hepatic glycogen stores to work (ineffective in starvation/alcohol-induced hypoglycemia).
Effects
## Glucagon — System-by-System Effects ### Metabolic/Hepatic System (Primary) - **Hepatic glycogenolysis**: Glucagon's primary physiological role is to stimulate glycogen breakdown in the liver, releasing glucose into the bloodstream. This is the counter-regulatory response to hypoglycemia. [Tier 1 — textbook endocrinology] - **Hepatic gluconeogenesis**: Stimulates de novo glucose production from amino acids, lactate, and glycerol. This sustains blood glucose during prolonged fasting after glycogen stores are depleted. [Tier 1] - **Blood glucose elevation**: Rapid and reliable blood glucose increase. Injectable glucagon raises blood glucose by 30-100 mg/dL within 10-15 minutes. [Tier 1 — extensive clinical data] - **Lipolysis stimulation**: Promotes fatty acid release from adipose tissue. This is secondary to its glucose effects but relevant for metabolic regulation. [Tier 1] - **Ketogenesis**: Stimulates hepatic ketone body production. Glucagon/insulin ratio is a key determinant of ketosis. [Tier 1] ### Cardiovascular System - **Positive inotropic effect**: Glucagon increases cardiac contractility and heart rate independent of beta-adrenergic receptors. This is why glucagon is used for beta-blocker overdose. [Tier 1] - **Vasodilation**: Mild vasodilatory effect. [Tier 1] ### Gastrointestinal System - **Smooth muscle relaxation**: Glucagon relaxes GI smooth muscle. Used diagnostically before GI imaging (barium studies, CT enterography) to reduce motility artifacts. [Tier 1 — established clinical use] - **Gastric emptying delay**: Slows gastric emptying. [Tier 1] ### Endocrine System - **Insulin secretion**: Glucagon stimulates insulin release from beta cells (paracrine islet signaling). This creates a feedback loop that prevents excessive hyperglycemia. [Tier 1] - **GLP-1 connection**: Glucagon and GLP-1 are both derived from proglucagon via tissue-specific processing. Understanding this relationship is key to modern metabolic pharmacology (dual agonists like tirzepatide). [Tier 1]
Practitioner Guide
## Glucagon — Practitioner Guide ### Clinical Profile Glucagon is a 29-amino acid peptide hormone produced by pancreatic alpha cells. It is the primary counter-regulatory hormone to insulin. Clinical use is primarily for hypoglycemia rescue and diagnostic procedures. ### Approved Clinical Uses 1. **Severe hypoglycemia rescue**: The primary indication. Used when a patient cannot take oral glucose (unconscious, seizing, or unable to swallow). - **Injectable glucagon kits**: 1mg IM or SC. Reconstitute powder and inject. Blood glucose rises within 10-15 minutes. - **Nasal glucagon (Baqsimi)**: 3mg intranasal spray. No reconstitution needed. Game-changer for caregiver ease of use. - **Auto-injector (Gvoke)**: Pre-mixed, ready to inject. 0.5mg for pediatric, 1mg for adult. - **Dasiglucagon (Zegalogue)**: Stable liquid formulation glucagon analog. 2. **Beta-blocker/calcium channel blocker overdose**: 3-10mg IV bolus followed by infusion. Glucagon bypasses blocked beta receptors to provide cardiac inotropy. [Tier 1 — emergency medicine standard of care] 3. **Diagnostic GI imaging**: 0.25-2mg IV or IM to reduce GI motility during radiological procedures. [Tier 1] ### Practical Considerations for Peptide Practitioners - **Every diabetic patient on insulin should have a glucagon rescue kit**: This is standard of care. Ensure patients AND their family members/caregivers know how to use it. - **Nasal glucagon (Baqsimi)**: Preferred for patients/caregivers who are needle-averse. Works even in unconscious patients. - **Storage**: Traditional glucagon kits require reconstitution and have limited stability. Newer formulations (Gvoke, Zegalogue) are pre-mixed and more practical. - **Training**: Prescribing glucagon without training caregivers on its use is inadequate. Schedule training sessions. ### Glucagon in the Context of GLP-1 Therapy - Patients on GLP-1 receptor agonists (semaglutide, tirzepatide) occasionally develop hypoglycemia, especially if on concurrent sulfonylureas or insulin - Glucagon rescue remains effective in these patients - Dual GLP-1/glucagon agonists (survodutide, others) are in development for obesity — understanding both pathways is important - The glucagon receptor agonist component of dual agonists contributes to energy expenditure and lipid metabolism ### Safety - Nausea/vomiting is common after glucagon administration (30-40%) - Transient hyperglycemia is expected and not harmful in the acute setting - Contraindicated in pheochromocytoma (can trigger hypertensive crisis) - Contraindicated in insulinoma (paradoxical insulin release can worsen hypoglycemia) - Generally very safe when used appropriately
Research Summary
## Glucagon — Research Summary ### Tier 1 (Strong Clinical Evidence) - **Hypoglycemia rescue**: Decades of clinical use. Multiple formulations FDA-approved. Efficacy is unquestioned. - **Physiology**: Glucagon biology is textbook endocrinology with extensive basic and clinical research. - **Beta-blocker overdose**: Standard emergency medicine protocol with strong clinical evidence. - **Diagnostic use**: Established radiology practice. - **New formulations**: Baqsimi (nasal), Gvoke (auto-injector), Zegalogue (dasiglucagon) — all FDA-approved with Phase 3 RCT data. ### Tier 2 (Moderate Evidence) - **Dual agonist pharmacology**: GLP-1/glucagon dual agonists in Phase 2/3 trials for obesity (survodutide, others). Glucagon component adds energy expenditure and lipid metabolism benefits. - **Artificial pancreas systems**: Dual-hormone (insulin + glucagon) closed-loop systems are in development. Glucagon mini-doses prevent hypoglycemia in these systems. ### Tier 3 (Emerging) - **Glucagon receptor agonism for obesity**: Early-stage research on harnessing glucagon's energy expenditure effects for weight management. ### Key Research Gaps - Optimal role of glucagon component in multi-agonist obesity therapies - Long-term safety of glucagon receptor agonism for metabolic disease - Dual-hormone artificial pancreas systems need more real-world validation