GLP-1 Glossary: 50+ Terms Every Patient Should Know
A complete reference guide to GLP-1 medication terminology, from semaglutide to tirzepatide to compounded medications and beyond.
Updated August 2026 · Medically reviewed by Dr. Sarah Chen, MD
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A hormone produced in the gut that stimulates insulin secretion, suppresses glucagon, slows gastric emptying, and reduces appetite. GLP-1 receptor agonists are medications that mimic this hormone.
GLP-1 Receptor Agonist
A class of medications that activate GLP-1 receptors to produce weight loss and blood sugar control. Includes semaglutide, tirzepatide, liraglutide, and dulaglutide.
Semaglutide
A GLP-1 receptor agonist FDA-approved for weight loss (Wegovy) and diabetes (Ozempic). Produces ~15% weight loss. Available as weekly injection or daily pill (Rybelsus).
Tirzepatide
A dual GIP/GLP-1 receptor agonist FDA-approved for weight loss (Zepbound) and diabetes (Mounjaro). Produces ~20-22% weight loss — the most effective GLP-1 available.
Liraglutide
A GLP-1 receptor agonist FDA-approved for weight loss (Saxenda) and diabetes (Victoza). Daily injection producing ~8% weight loss. Less effective than semaglutide or tirzepatide.
Dulaglutide
A GLP-1 receptor agonist FDA-approved for diabetes (Trulicity). Weekly injection. Less effective for weight loss than semaglutide or tirzepatide.
Compounded Medication
A medication prepared by an FDA-registered compounding pharmacy rather than a commercial manufacturer. Legal during FDA-declared drug shortages. Compounded semaglutide costs $147-$399/month vs $1,300/month for Wegovy.
GIP (Glucose-Dependent Insulinotropic Polypeptide)
A hormone that, like GLP-1, stimulates insulin secretion. Tirzepatide activates both GIP and GLP-1 receptors, which is why it produces more weight loss than GLP-1-only medications.
Gastric Emptying
The process by which food leaves the stomach and enters the small intestine. GLP-1 medications slow gastric emptying, prolonging fullness and reducing post-meal blood sugar spikes.
Visceral Fat
Fat stored deep inside the abdomen around organs. Most metabolically dangerous fat type. GLP-1 medications preferentially reduce visceral fat by 30-40%.
Subcutaneous Fat
Fat stored just under the skin. Less metabolically dangerous than visceral fat. GLP-1s reduce subcutaneous fat by 15-25%.
Insulin Resistance
A condition where cells become less responsive to insulin, leading to higher blood sugar and fat storage. GLP-1 medications significantly improve insulin sensitivity.
Leptin
A hormone produced by fat cells that signals satiety to the brain. Many people with obesity develop leptin resistance, where the brain stops responding to leptin signals.
Ghrelin
The body's primary hunger hormone, produced by the stomach. GLP-1 medications counteract ghrelin's hunger signals through separate brain pathways.
Food Noise
A term patients use to describe constant mental preoccupation with food. GLP-1 medications dramatically reduce food noise for most patients.
Titration
The process of gradually increasing medication dose over weeks or months. GLP-1 titration reduces side effects by allowing the body to adapt slowly.
Maintenance Dose
A reduced dose taken after achieving weight loss goals to prevent regain. Typically 50-75% of the weight loss dose.
Lipohypertrophy
Lumps of hardened fat tissue under the skin caused by repeated injections in the same spot. Prevented by rotating injection sites.
Subcutaneous Injection
An injection into the fat layer under the skin (not muscle). GLP-1 medications are administered this way using very fine needles.
Bioavailability
The proportion of a medication that enters the bloodstream and has an active effect. Injectable semaglutide has ~100% bioavailability; oral semaglutide has ~1%.
Half-Life
The time for half of a medication to be cleared from the bloodstream. Semaglutide: ~7 days. Tirzepatide: ~5 days. Liraglutide: ~13 hours.
Telehealth
Healthcare delivered remotely via online consultations. Telehealth providers can prescribe GLP-1 medications after reviewing your medical history, without an in-person visit.
FDA-Registered Compounding Pharmacy
A pharmacy registered with the FDA that prepares customized medications following Current Good Manufacturing Practice (CGMP) standards.
503A Pharmacy
A traditional compounding pharmacy that prepares medications for individual patients with prescriptions. Regulated by state boards of pharmacy.
503B Pharmacy
An outsourcing facility registered with the FDA that can compound medications in bulk without individual prescriptions. Subject to federal CGMP requirements.
BMI (Body Mass Index)
A measure of body fat based on height and weight. GLP-1 eligibility typically requires BMI ≥30 or ≥27 with a weight-related condition.
HbA1c
A blood test measuring average blood sugar over 2-3 months. GLP-1 medications reduce HbA1c by 1.0-2.3%, indicating improved blood sugar control.
Metabolic Syndrome
A cluster of conditions (high blood pressure, high blood sugar, excess belly fat, abnormal cholesterol) that increase heart disease and diabetes risk. GLP-1s address multiple components.
PCOS (Polycystic Ovary Syndrome)
A hormonal disorder causing insulin resistance, irregular periods, and weight gain. GLP-1 medications can improve PCOS symptoms by improving insulin sensitivity.
Retatrutide
An investigational triple receptor agonist (GLP-1 + GIP + glucagon) in Phase 3 trials. Phase 2 data showed ~24% weight loss — more than any current GLP-1.
Orforglipron
An investigational oral GLP-1 receptor agonist (pill form) by Eli Lilly. In Phase 3 trials. Could be the first convenient oral GLP-1 without injection.
CagriSema
An investigational combination of semaglutide and cagrilintide (a amylin analog). In Phase 3 trials. May produce ~25% weight loss.
Wegovy
Brand name for FDA-approved semaglutide for weight loss. Weekly injection. Costs ~$1,300/month without insurance. Wegovy pill approved December 2025.
Ozempic
Brand name for FDA-approved semaglutide for type 2 diabetes. Same active ingredient as Wegovy but typically prescribed for diabetes. Costs ~$900/month.
Zepbound
Brand name for FDA-approved tirzepatide for weight loss. Weekly injection. Costs ~$1,060/month without insurance.
Mounjaro
Brand name for FDA-approved tirzepatide for type 2 diabetes. Same active ingredient as Zepbound. Costs ~$1,080/month.
Rybelsus
Brand name for FDA-approved oral semaglutide (daily pill) for type 2 diabetes. Same active ingredient as Ozempic/Wegovy but in pill form.
Saxenda
Brand name for FDA-approved liraglutide for weight loss. Daily injection. Less effective than semaglutide or tirzepatide.
Trulicity
Brand name for FDA-approved dulaglutide for type 2 diabetes. Weekly injection. Less effective for weight loss than other GLP-1s.
Novo Nordisk
Danish pharmaceutical company that manufactures Wegovy, Ozempic, and Rybelsus (semaglutide products).
Eli Lilly
American pharmaceutical company that manufactures Zepbound, Mounjaro (tirzepatide), and is developing retatrutide and orforglipron.
STEP Trials
Clinical trials that established semaglutide's efficacy for weight loss. Showed ~15% weight loss over 68 weeks.
SURMOUNT Trials
Clinical trials that established tirzepatide's efficacy for weight loss. Showed ~20-22% weight loss over 72 weeks.
SURMOUNT-OSA
Clinical trial showing tirzepatide reduced sleep apnea severity by 62-68% in patients with obesity and moderate-to-severe OSA.
Adaptive Thermogenesis
The body's tendency to reduce resting metabolic rate beyond what is expected from weight loss alone. A normal response that can slow weight loss.
Ozempic Face
A term describing facial fat loss from rapid overall weight loss on GLP-1 medications. Not specific to the face — it's a normal effect of significant fat loss.
Gastroparesis
Severe delayed gastric emptying. A rare but serious risk of GLP-1 medications. Symptoms include persistent vomiting and early fullness.
MTC (Medullary Thyroid Carcinoma)
A rare thyroid cancer. GLP-1 medications are contraindicated for patients with personal or family history of MTC due to animal study findings.
MEN2 (Multiple Endocrine Neoplasia type 2)
A genetic syndrome increasing risk of thyroid cancer. GLP-1 medications are contraindicated for patients with MEN2.
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Related GLP-1 Resources
Medical disclaimer: This glossary is for informational purposes only and is not medical advice. GLP-1 medications are prescription products requiring a physician consultation. Affiliate disclosure: This page contains affiliate links. We may earn a commission if you sign up through them, at no extra cost to you.