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- Class 1: Pure GLP-1 receptor agonists
- Class 2: Non-peptide oral GLP-1 agonists
- Class 3: Dual GIP/GLP-1 receptor agonists
- Class 4: Dual glucagon/GLP-1 receptor agonists
- Class 5: Triple GLP-1/GIP/glucagon receptor agonists
- Class 6: Amylin/GLP-1 combinations
- What this means for choosing treatment today
- Related guides
GLP-1 peptide classes explained: single, dual, and triple agonists
Understanding the difference between pure GLP-1 agonists, dual GIP/GLP-1 agonists, glucagon combinations, and amylin hybrids helps you make sense of the rapidly expanding weight-loss drug landscape.
By GLP-1 Scout Editorial Team · Published April 5, 2026
The term "GLP-1 medication" has become an umbrella label for a growing family of drugs that actually work through different receptor combinations. Understanding these classes helps patients evaluate both current medications and the pipeline drugs that will reach the market over the next 2-3 years. Each class trades off differently between weight loss magnitude, side effect profile, metabolic benefits, and convenience.
Class 1: Pure GLP-1 receptor agonists
These drugs activate only the GLP-1 receptor. They are the most established class with the longest clinical track record.
Approved drugs: semaglutide (Wegovy, Ozempic), liraglutide (Saxenda, Victoza), oral semaglutide (Wegovy pill, Rybelsus).
Mechanism: appetite suppression via hypothalamic signaling, delayed gastric emptying, glucose-dependent insulin secretion.
Weight loss range: 8-17% depending on drug and dose.
Key advantage: longest safety track record, cardiovascular outcome data (SELECT trial), both injectable and oral options available.
Key limitation: single-pathway approach produces less weight loss than multi-receptor drugs.
Class 2: Non-peptide oral GLP-1 agonists
A newer subclass that uses small-molecule chemistry instead of peptide engineering to activate the GLP-1 receptor. The key advantage is better oral bioavailability — no fasting requirements.
Approved drugs: orforglipron (Foundayo).
Discontinued: danuglipron (Pfizer, shelved April 2025 after liver toxicity signal).
Weight loss range: ~12% at maximum dose.
Key advantage: oral, no injection, no food timing restrictions, lower price point.
Key limitation: lower weight loss than injectable peptides; limited long-term safety data.
Class 3: Dual GIP/GLP-1 receptor agonists
These drugs activate both GLP-1 and GIP (glucose-dependent insulinotropic polypeptide) receptors. Adding GIP agonism improves insulin sensitivity and alters fat distribution.
Approved drugs: tirzepatide (Zepbound, Mounjaro).
Pipeline: VK2735 (Viking Therapeutics, Phase 3).
Weight loss range: 15-23% depending on dose.
Key advantage: highest approved weight loss; tirzepatide’s three maintenance dose levels (5, 10, 15 mg) offer prescribing flexibility.
Key limitation: injectable only; limited cardiovascular outcome data compared to semaglutide.
Class 4: Dual glucagon/GLP-1 receptor agonists
Adding glucagon receptor activation introduces an energy-expenditure component and direct liver fat mobilization. This class is particularly promising for MASH (liver disease).
Pipeline drugs: survodutide (Boehringer Ingelheim, Phase 3), pemvidutide (Altimmune, Phase 2, FDA Breakthrough Therapy for MASH).
Weight loss range: ~19% (survodutide Phase 2).
Key advantage: direct liver fat reduction makes these dual-purpose obesity + MASH drugs.
Key limitation: higher GI discontinuation rates (~25% at highest doses in Phase 2); glucagon component can affect blood glucose regulation.
Class 5: Triple GLP-1/GIP/glucagon receptor agonists
The only drug in this class is retatrutide, which activates all three incretin and counter-regulatory pathways simultaneously.
Pipeline drugs: retatrutide (Eli Lilly, Phase 3 TRIUMPH program).
Weight loss: 28.7% at 68 weeks in Phase 3 — the highest ever recorded.
Key advantage: largest weight loss, additional metabolic rate increase, liver fat mobilization.
Key limitation: not yet approved; unique dysesthesia side effect (20.9% at 12 mg); dose-dependent heart rate increase.
Class 6: Amylin/GLP-1 combinations
Amylin is a pancreatic hormone that provides satiety signaling through a different pathway than GLP-1. Combining the two produces additive appetite suppression.
Pipeline drugs: CagriSema (Novo Nordisk, NDA filed — two separate drugs in one injection), amycretin (Novo Nordisk, Phase 2/3 — single molecule activating both receptors).
Weight loss: 22-23% (CagriSema Phase 3), 22% at 36 weeks (amycretin Phase 1b/2a).
Key advantage: amycretin’s oral formulation showed 13% loss at just 12 weeks in early data.
Key limitation: CagriSema lost to tirzepatide in head-to-head trial (23% vs 25.5%); high GI event rates (~80%).
| Class | Receptors | Best current drug | Max weight loss | Status |
|---|---|---|---|---|
| Pure GLP-1 | GLP-1 only | Semaglutide (Wegovy) | ~17% | Approved |
| Non-peptide oral GLP-1 | GLP-1 only | Orforglipron (Foundayo) | ~12% | Approved |
| Dual GIP/GLP-1 | GLP-1 + GIP | Tirzepatide (Zepbound) | ~23% | Approved |
| Dual Glucagon/GLP-1 | GLP-1 + Glucagon | Survodutide | ~19% | Phase 3 |
| Triple agonist | GLP-1 + GIP + Glucagon | Retatrutide | ~29% | Phase 3 |
| Amylin/GLP-1 | GLP-1 + Amylin | CagriSema | ~23% | NDA filed |
What this means for choosing treatment today
For patients starting treatment in 2026, the practical choices are pure GLP-1 (semaglutide), dual GIP/GLP-1 (tirzepatide), non-peptide oral GLP-1 (orforglipron), or liraglutide. The pipeline drugs will begin reaching the market in late 2026 (CagriSema) through 2028 (retatrutide). Understanding the classes helps patients have more informed conversations with their prescribers about which drug — current or future — fits their goals, risk tolerance, and budget.