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GLP-1 Medical Glossary
20 plain-English definitions of common terms. Clinician-reviewed.
A
- A1C (HbA1c)
- A blood test that measures average blood glucose over the past 2-3 months. A1C ≥6.5% indicates diabetes. GLP-1 medications typically lower A1C by 1-2 percentage points.
B
- BMI (Body Mass Index)
- A screening calculation of body weight relative to height (kg/m²). FDA-approved weight-management GLP-1s require BMI ≥30, or ≥27 with a weight-related comorbidity.
- Bioavailability
- The proportion of a drug that reaches systemic circulation in active form. Injectable GLP-1s (Wegovy, Mounjaro) have higher bioavailability than oral semaglutide (Rybelsus).
See also: Comorbidity
C
- Compounded medication
- A medication custom-prepared by a licensed compounding pharmacy, often using the same active ingredient as a brand-name drug. The FDA allowed compounded semaglutide during the 2022-2025 shortage; access has tightened since.
- Comorbidity
- A second medical condition occurring with the primary one. Hypertension, type 2 diabetes, dyslipidemia, and obstructive sleep apnea are common weight-related comorbidities that lower the BMI threshold for GLP-1 eligibility to 27.
- Contraindication
- A specific situation in which a drug should not be used. GLP-1 contraindications include personal or family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2 (MEN 2).
F
- FDA prescribing information (PI)
- The official drug label, including approved uses, dosing, contraindications, warnings, and clinical trial data. Located on accessdata.fda.gov. The primary citation source for every medication page on this site.
G
- GIP (glucose-dependent insulinotropic polypeptide)
- A gut hormone that stimulates insulin release after meals. Tirzepatide is a dual GIP/GLP-1 receptor agonist; semaglutide acts only on GLP-1 receptors.
- GLP-1 (glucagon-like peptide-1)
- A naturally-occurring gut hormone that slows gastric emptying, reduces appetite, and improves insulin response. GLP-1 receptor agonist medications mimic this hormone.
See also: GIP
I
- Indication
- A specific medical condition for which a drug is FDA-approved. Wegovy is indicated for chronic weight management; Ozempic is indicated for type 2 diabetes. Off-label use is legal but uninsured.
M
- Maintenance dose
- The final stable dose of a medication, reached after a titration schedule. Wegovy maintenance is 2.4 mg weekly; Zepbound maintenance ranges from 5–15 mg weekly.
See also: Titration
O
- Off-label use
- Prescribing an FDA-approved drug for a condition it is not approved for. Using Ozempic for weight loss is off-label since Ozempic is approved only for type 2 diabetes; insurance typically refuses coverage in this scenario.
P
- Pen / autoinjector
- The prefilled, multi-dose delivery device used for most injectable GLP-1s. Each pen contains 4 weeks of medication and a built-in needle that retracts after injection.
R
- RxNorm code (RxCUI)
- A standardized identifier maintained by the U.S. National Library of Medicine that uniquely identifies clinical drugs. Used to cross-reference drugs across FDA, insurance, and EHR systems.
S
- Semaglutide
- A long-acting GLP-1 receptor agonist sold as Ozempic (diabetes), Wegovy (weight management), and Rybelsus (oral diabetes formulation). All three are made by Novo Nordisk.
T
- Telehealth
- Healthcare delivered remotely via secure video, phone, or asynchronous messaging. All providers reviewed on this site offer telehealth GLP-1 consultations. State medical licensing varies — providers must be licensed in your state to prescribe.
- Tirzepatide
- A dual GIP/GLP-1 receptor agonist sold as Mounjaro (diabetes) and Zepbound (weight management). Made by Eli Lilly. In head-to-head trials, tirzepatide achieved greater mean weight loss than semaglutide.
- Titration
- The gradual increase of a medication dose over weeks to reduce side effects. GLP-1 titration typically takes 16-20 weeks before reaching the full maintenance dose.
See also: Maintenance dose
Y
- YMYL ("Your Money or Your Life")
- Google's classification for content that could impact a person's health, finances, or safety. YMYL content faces higher editorial standards from search ranking algorithms — every page on this site is reviewed by a licensed clinician to meet that bar.