GLP-1 Glossary: Every Term Explained, A to Z

GLP-1 treatment comes with its own vocabulary, terms that can be confusing the first time you encounter them. This glossary defines every term used across this knowledge base in one place, so you never have to guess what a word means mid-article.

A1C: A blood test measuring average blood sugar over roughly the past 2-3 months, used to track diabetes management and treatment response.

AHI (Apnea-Hypopnea Index): The standard measure of obstructive sleep apnea severity, counting breathing interruptions per hour of sleep.

Beyond-Use Date: The date after which a compounded medication should no longer be used, set by the compounding pharmacy, distinct from a manufacturer expiration date.

Bridge Program: The Medicare GLP-1 Bridge, a 2026 demonstration program covering Wegovy, Zepbound, and Foundayo for weight loss at a flat $50 monthly copay.

Compounded Medication: A version of a drug prepared by a compounding pharmacy rather than manufactured by the original drug company, not FDA-approved.

Dose Escalation: The gradual, planned increase of a medication dose over time, also called titration, designed to reduce side effects.

Dual Agonist: A medication that activates two different hormone receptors at once, such as tirzepatide's action on both GLP-1 and GIP receptors.

Food Noise: Persistent, intrusive thoughts about food that feel difficult to control, often quieted by GLP-1 medications through dampened brain reward signaling.

GIP (Glucose-Dependent Insulinotropic Polypeptide): A gut hormone receptor targeted alongside GLP-1 by dual-agonist medications like tirzepatide.

GLP-1 (Glucagon-Like Peptide-1): A natural gut hormone that regulates blood sugar and appetite, and the receptor target that gives this medication class its name.

Lipohypertrophy: A buildup of fatty tissue under the skin from repeated injections in the same spot, which can affect medication absorption.

Maintenance Dose: The target, ongoing dose a patient reaches after completing dose escalation, intended for long-term use.

MASLD / MASH: Metabolic dysfunction-associated steatotic liver disease (MASLD) and its more severe inflammatory form, MASH, both linked to obesity and metabolic health.

MEN 2 (Multiple Endocrine Neoplasia Syndrome Type 2): A rare genetic condition that is a contraindication for GLP-1 medications due to thyroid tumor risk.

MTC (Medullary Thyroid Carcinoma): A type of thyroid cancer observed in rodent studies of GLP-1 medications, the basis for the class's boxed warning.

NDA (New Drug Application): The formal application a drug manufacturer submits to the FDA seeking approval for a new medication.

Off-Label Use: Prescribing a medication for a purpose other than its FDA-approved indication, legal but not covered by the same evidence or insurance guarantees.

Prior Authorization: An insurance requirement where a doctor must document medical necessity before a medication is covered.

Subcutaneous Injection: An injection delivered into the fatty tissue just under the skin, the method used for all GLP-1 injectable medications.

Titration: See Dose Escalation, the gradual, stepwise increase of a medication dose over time.

Triple Agonist: A medication activating three hormone receptors at once, such as retatrutide's action on GLP-1, GIP, and glucagon receptors.

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This glossary is updated as new terms come up across our medication, symptom, and research pages. If you came across a term elsewhere on DietApp.com that isn't defined here, it's likely explained in context on the page where you found it.

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About DietApp.com

DietApp.com combines evidence-based GLP-1 medication education with practical treatment tracking tools. This glossary is for general informational purposes and is not medical advice.