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Glossary

GLP-1 glossary

The words that come up around GLP-1 medicines — on labels, in trial results, at the pharmacy and in the app — explained in plain English. 45 terms, each linked to the guide that goes further.

By the Cafeity teamUpdated

A

Adverse reaction
An unwanted effect that has a reasonable chance of being caused by a medicine. Prescribing information lists the adverse reactions seen in trials next to the rate on placebo, so you can see how much is down to the medicine itself — for example, nausea in 44% of people on semaglutide 2.4 mg against 16% on placebo.1 See GLP-1 side effects.
Agonist
A substance that switches a receptor on, the way a key turns a lock. A GLP-1 receptor agonist switches on the receptor that the body's own GLP-1 hormone uses. See GLP-1 receptor agonist.
Aspiration (pulmonary)
Stomach contents getting into the lungs. Because GLP-1 medicines slow stomach emptying, the labels describe rare reports of aspiration during general anaesthesia or deep sedation, and ask patients to tell their healthcare providers about the medicine before any planned surgery or procedure.1

B

BMI (body mass index)
Weight in kilograms divided by the square of height in metres. The main weight-management trials enrolled adults with a BMI of 30 or more, or 27 or more with a weight-related condition.23 BMI cannot tell fat from muscle; see body composition.
Body composition
How body weight divides between fat mass and lean mass — muscle, organs, bone and water. In the SURMOUNT-1 body-composition substudy, tirzepatide reduced fat mass by 33.9% and lean mass by 10.9% over 72 weeks.4 See muscle loss on a GLP-1.
Boxed warning
The most prominent warning in US prescribing information, printed in a box at the top of the label. Most GLP-1 labels carry one about thyroid C-cell tumours seen in rodents; the twice-daily exenatide label does not.15 See medullary thyroid carcinoma.

C

Compounded medicine
A medicine prepared by a pharmacy rather than made by an approved manufacturer. Compounded versions of semaglutide and tirzepatide are not FDA-approved, and the FDA has reported dosing errors with them.67 See compounded GLP-1s.
Contraindication
A situation in which a medicine must not be used. For most GLP-1 medicines these include a personal or family history of medullary thyroid carcinoma or MEN 2, and a previous serious allergic reaction to the medicine.18
Cycle View
Cafeity's chart of an estimated medication level, drawn from the doses you log and the half-life in the prescribing information. It is labelled on screen as an estimate, because it is a model, not a blood test. See the Cycle View.

D

Delayed gastric emptying
Food leaving the stomach more slowly than usual. GLP-1 medicines cause it, which contributes to feeling full sooner — and to nausea, to the anaesthesia warning, and to changes in how some tablets taken by mouth are absorbed.18
Dose escalation
Starting a medicine at a low dose and increasing it in steps over weeks or months, also called titration. The labels set out an escalation schedule to reduce the risk of gastrointestinal side effects, which are most common while the dose is going up.9 Your prescriber sets the steps; Cafeity never suggests them. See the side-effects timeline.
DXA scan
Dual-energy X-ray absorptiometry: a low-dose scan that measures fat, lean mass and bone. It is how trials measure body composition.4
Dysaesthesia
Altered skin sensation — tingling, burning or skin that hurts to touch. With semaglutide it became more common at higher doses; in the 25 mg tablet trial it was reported by 5% of people and by no one on placebo.1 See skin sensitivity.

F

Food noise
An informal name for persistent, intrusive thoughts about food. It is not a diagnosis and has only recently been studied, but many people on GLP-1 medicines describe it growing quieter.10 See food noise.

G

Gastroparesis
A condition in which the stomach empties very slowly without any blockage. The semaglutide weight-management label says the medicine is not recommended for people with severe gastroparesis.1
Generic name
The official non-proprietary name of a medicine's active ingredient, such as semaglutide or tirzepatide. One generic medicine can be sold under several brand names and strengths. Cafeity uses generic names throughout. See the GLP-1 medicines explained.
GIP
Glucose-dependent insulinotropic polypeptide, a second gut hormone involved in blood-sugar control. Tirzepatide activates both the GIP and the GLP-1 receptors.9 See semaglutide vs tirzepatide.
GLP-1
Glucagon-like peptide-1, a hormone released by the gut after eating that helps regulate blood sugar and appetite. The body breaks its own GLP-1 down within minutes — its half-life is 1.5 to 2 minutes.11
GLP-1 receptor agonist
A medicine that activates the GLP-1 receptor but lasts far longer than the natural hormone — from hours to about a week. Semaglutide, tirzepatide, liraglutide, dulaglutide, exenatide and orforglipron are all GLP-1 receptor agonists; tirzepatide also acts on GIP.198

H

Half-life
The time it takes for the amount of a medicine in the blood to fall by half: about a week for semaglutide, about five days for tirzepatide and about 13 hours for liraglutide.1911 After about five half-lives only around 3% is left. See how long semaglutide stays in your system.
Line chart of how a single dose declines over 14 days for four GLP-1 medicines, from their label half-lives: semaglutide falls to about 25% after two weeks and tirzepatide to about 14%, while orforglipron falls to about 5% after one week and liraglutide to under 10% within two days.
One dose of each, from the published half-lives.
Hypoglycaemia
Low blood sugar. The labels warn that the risk rises when a GLP-1 medicine is taken with insulin or with a medicine that makes the body release more insulin, such as a sulfonylurea.1 Signs include shakiness, sweating, hunger, confusion and a fast heartbeat.

I

Indication
A use a medicine is approved for, as listed in section 1 of its prescribing information — for example weight management, type 2 diabetes or reducing cardiovascular risk. See what each medicine is approved for.
Injection site
Where an injection goes under the skin. The labels list the abdomen, the thigh and the upper arm — for some pens, the back of the upper arm, injected by someone else — and say to change the site with each injection.19 See the site rotation chart.
Front and back body outlines showing eight numbered injection zones: 1 to 4 in the four quarters of the abdomen around a circle marking 5 cm from the navel, 5 and 6 on the front of the left and right thighs, and 7 and 8 on the back of the left and right upper arms.
The zones used on the printable rotation chart.
Intention-to-treat
A way of analysing a trial that counts everyone in the group they were randomised to, including people who stopped taking the medicine. It gives a more cautious average than counting only those who kept going. The semaglutide tablet result quoted on this site — −13.6% at 64 weeks against −2.4% on placebo — is an intention-to-treat figure.1

L

Label (prescribing information)
The official document the FDA approves for each medicine, setting out what it is approved for, how it is taken, its warnings and its trial results. US labels are published on DailyMed, and every medicine figure on this site is quoted from one.12
Lean mass
Everything in the body that is not fat: muscle, organs, bone and water. Lean mass is not the same as muscle. See body composition.

M

MASH
Metabolic dysfunction-associated steatohepatitis: inflammation and damage in a liver holding too much fat, formerly called NASH. Semaglutide is approved for noncirrhotic MASH with moderate to advanced liver fibrosis.1
Medullary thyroid carcinoma and MEN 2
A rare thyroid cancer, and an inherited condition (multiple endocrine neoplasia type 2) that raises its risk. Most GLP-1 labels say the medicine must not be used by anyone with a personal or family history of either, and ask patients to report a lump in the neck, trouble swallowing, shortness of breath or persistent hoarseness.18
MedWatch
The FDA's programme for reporting side effects and problems with medical products. Anyone can report, not only clinicians. The UK equivalent is the Yellow Card scheme.1314

O

Obstructive sleep apnoea
Repeated narrowing or collapse of the upper airway during sleep, interrupting breathing. Tirzepatide is approved to treat moderate to severe obstructive sleep apnoea in adults with obesity.9 See sleep on a GLP-1.
Off-label use
Prescribing an approved medicine for a purpose, dose or group of people not listed on its label. It is a clinical decision for the prescriber, and the label's trial evidence does not cover that use.
Ora
Cafeity's assistant, which answers questions about your own record. Every number it mentions is calculated by the app first, and it never gives dose instructions. See Ora.
Oral semaglutide
Semaglutide as a daily tablet. It is taken on an empty stomach with up to 120 ml (4 oz) of plain water, then nothing to eat, drink or swallow for at least 30 minutes.1 See the oral semaglutide tracker.

P

Pancreatitis
Inflammation of the pancreas. The labels warn about it and describe the main sign as persistent, severe abdominal pain, sometimes spreading to the back, with or without vomiting — a reason to stop the medicine and get medical care promptly.1
Peak level
The point after a dose when the amount in the blood is highest: 1 to 3 days after a semaglutide injection, and a median of 24 hours (range 8 to 72) after tirzepatide.19
Placebo
An inactive dummy treatment given to one group in a trial so that the medicine's effects can be separated from everything else, including the diet and activity advice that placebo groups usually receive too. In STEP 1, the placebo group lost an average of 2.4% of body weight over 68 weeks.2
Plateau
A stretch of weeks when weight stops falling. In STEP 1, average weight on semaglutide reached its lowest point around week 60.2 See weight-loss plateaus.
Prior authorization
A US insurer's requirement to approve a medicine before it will cover it, usually based on records from your prescriber. See records for prior authorization.

S

Small-molecule GLP-1
A GLP-1 receptor agonist that is not a peptide. Orforglipron is one: a chemically made molecule taken as a daily tablet, with or without food.8 See the orforglipron tracker.
Steady state
The point at which the amount of medicine absorbed from each dose balances the amount eliminated, so levels rise and fall within the same range from one dose to the next. For once-weekly semaglutide, it is reached after 4 to 5 weeks.15
Sulphur burps
Burps that smell of rotten eggs. Burping (eructation) was reported by 7% of people on semaglutide 2.4 mg against under 1% on placebo.1 See sulphur burps.

T

Telogen effluvium
Temporary hair shedding that usually starts two to three months after a physical stress such as illness, surgery or rapid weight loss, and lasts around three to six months.16 See hair loss on a GLP-1.
Titration
Another name for dose escalation.

V

Visit Summary
Cafeity's one-page report of a period you choose — doses, weight trend, symptoms and food — to print or share with your prescriber. See the Visit Summary.

W

Weight trend
A smoothed average of daily weights that damps the day-to-day swings from water, salt and digestion, so the direction is easier to see. In Cafeity it is labelled as based on your recent rate, not a prediction. See weight-loss plateaus.
Illustration over ten weeks: grey dots for daily weigh-ins scatter up and down by about a kilogram around a violet smoothed trend line that falls steadily and then flattens from week six, where the chart is shaded and labelled "trend flattens". Marked as an illustration, not real data.
Daily weigh-ins scatter; the trend shows the direction. An illustration, not real data.

Sources

  1. Semaglutide injection and tablets for weight management — US prescribing information DailyMed, US National Library of Medicine, version published 30 June 2026
  2. Once-weekly semaglutide in adults with overweight or obesity (STEP 1) Wilding JPH et al. New England Journal of Medicine 2021;384:989–1002
  3. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1) Jastreboff AM et al. New England Journal of Medicine 2022;387:205–216
  4. Body composition changes during weight reduction with tirzepatide in the SURMOUNT-1 study Look M et al. Diabetes, Obesity and Metabolism 2025
  5. Exenatide twice-daily injection — US prescribing information DailyMed, US National Library of Medicine, version published 8 September 2025
  6. FDA's concerns with unapproved GLP-1 drugs used for weight loss US Food and Drug Administration
  7. Compounding risk alerts (including dosing errors with compounded injectable semaglutide, July 2024) US Food and Drug Administration
  8. Orforglipron tablets for weight management — US prescribing information DailyMed, US National Library of Medicine, version published 13 August 2026
  9. Tirzepatide injection for weight management and obstructive sleep apnoea — US prescribing information DailyMed, US National Library of Medicine, version published 2 September 2026
  10. Food noise: definition, measurement, and future research directions Nutrition & Diabetes 2025
  11. Liraglutide 3 mg injection for weight management — US prescribing information DailyMed, US National Library of Medicine, version published 15 June 2026
  12. DailyMed — search current US prescribing information US National Library of Medicine
  13. MedWatch — report a side effect to the FDA US Food and Drug Administration
  14. Yellow Card — report a suspected side effect (UK) Medicines and Healthcare products Regulatory Agency
  15. Semaglutide injection for type 2 diabetes — US prescribing information DailyMed, US National Library of Medicine, version published 10 June 2026
  16. Telogen effluvium: symptoms, causes, treatment and regrowth Cleveland Clinic

Written by the Cafeity team from the sources listed here. Figures from prescribing information are quoted as the label states them; trial results are averages from those trials, not predictions for any one person. This page has not yet been reviewed by a clinician — see the editorial policy for how pages are researched and corrected.