What's the Difference Between GLP-2 and GLP-3?
In the research-peptide market, "GLP-2" and "GLP-3" describe how many receptors a compound activates, not two different hormones. GLP-2 TRZ is a dual agonist (GIP + GLP-1). GLP-3 RT is a triple agonist (GIP + GLP-1 + glucagon). The numbers are catalog shorthand. They are unrelated to the endogenous hormone GLP-2 (glucagon-like peptide-2), which is a separate intestinal peptide.
"GLP-2 TRZ" is tirzepatide, not glucagon-like peptide-2. If a paper or listing discusses GLP-2 in the context of gut mucosal growth, it is talking about a different molecule.
GLP-3 RT vs GLP-2 TRZ: Side-by-Side Specs
| Property | GLP-3 RT (retatrutide) | GLP-2 TRZ (tirzepatide) |
|---|---|---|
| Receptors activated | GIPR + GLP-1R + GCGR | GIPR + GLP-1R |
| Agonist class | Triple (tri-agonist) | Dual (twincretin) |
| Length | 39 amino acids | 39 amino acids |
| Molecular weight | ~4,731 Da | ~4,813 Da |
| Half-life extension | C20 fatty diacid (albumin binding) | C20 fatty diacid (albumin binding) |
| Reported half-life | ~6 days | ~5 days |
| Development code | LY3437943 | LY3298176 |
| Developer | Eli Lilly | Eli Lilly |
| Approval status (Sep 2026) | Investigational | FDA-approved drug |
| Evo Peptides name | EP-3 RT | EP-2T |
Use the molecular weight row when you read a COA: mass spectrometry should land near ~4,731 Da for GLP-3 RT and ~4,813 Da for GLP-2 TRZ. For the full method, see How to Read a Peptide COA.
Receptor Profile: Why the Glucagon Arm Matters
Glucagon-receptor agonism is the one mechanism GLP-3 RT has that GLP-2 TRZ does not. Glucagon signaling is studied for its effects on hepatic glucose output, lipid oxidation and energy expenditure. Pairing it with GLP-1 and GIP agonism is the design choice that separates a triple agonist from a dual one.
Deeper mechanism reviews: GLP-3 RT research guide and GLP-2 TRZ research guide.
GLP-3 RT and GLP-2 TRZ: Names and Aliases
| Compound | Also sold or searched as |
|---|---|
| GLP-3 RT | Retatrutide, LY3437943, EP-3 RT, RT3, Reta, GLP3-RT, GLP-3 RTA, GLP-3 (R) |
| GLP-2 TRZ | Tirzepatide, LY3298176, EP-2T, TRZ, TRZ-2, G2-TRZ, GLP-2 TZ, GLP-2 (T) |
Clinical and Regulatory Status (September 2026)
| Milestone | Retatrutide (GLP-3 RT) | Tirzepatide (GLP-2 TRZ) |
|---|---|---|
| Phase 3 program | TRIUMPH trials; several completed in 2026, outcomes trials still active | SURPASS and SURMOUNT programs completed |
| FDA status | Not approved; investigational | Approved as Mounjaro (2022) and Zepbound (2023) |
| Research-grade material | RUO reagent only | RUO reagent only (not the branded drug) |
Research-grade GLP-3 RT and GLP-2 TRZ are laboratory reagents sold for in vitro research. Neither is the branded pharmaceutical, and neither is for human or veterinary use.
Price per mg and Current Batch Data
GLP-2 TRZ is the cheaper compound per milligram: $2.50/mg on the 30mg vial versus $4.50/mg for GLP-3 RT. Both current lots tested above 99.5% HPLC purity with net peptide content at or above label.
| Vial | Price | $ / mg | Lot | HPLC purity | Net content |
|---|---|---|---|---|---|
| GLP-3 RT 15mg | $69.95 | $4.66 | RT0006 | 99.72% | 16.94mg |
| GLP-3 RT 20mg | $89.95 | $4.50 | — | — | — |
| GLP-3 RT 30mg | $134.95 | $4.50 | RT0006 | 99.57% | 31.49mg |
| GLP-2 TRZ 15mg | $49.95 | $3.33 | TRZ0001 | 99.91% | 15.81mg |
| GLP-2 TRZ 30mg | $74.95 | $2.50 | TRZ0001 | 99.76% | 31.50mg |
Full certificates are in the COA library. Buying details for the triple agonist are in the GLP-3 RT buying guide.
GLP-3 RT or GLP-2 TRZ: Which One to Use in a Study?
| If your study needs… | Use | Why |
|---|---|---|
| Glucagon-receptor or energy-expenditure endpoints | GLP-3 RT | Only the triple agonist engages GCGR |
| A benchmark tied to an approved drug's molecule | GLP-2 TRZ | Tirzepatide has the larger published literature |
| To isolate what the glucagon arm adds | Both | Run them side by side; the difference is the GCGR contribution |
| The lowest cost per mg | GLP-2 TRZ | $2.50/mg on the 30mg vial |
For timing between administrations in study design, see the peptide half-life chart. For handling, see the peptide storage guide.
Glossary
| Term | Definition |
|---|---|
| Incretin | A gut hormone (GLP-1 or GIP) that increases glucose-dependent insulin secretion. |
| Dual agonist | One molecule that activates two receptors, here GIPR and GLP-1R. |
| Triple agonist | One molecule that activates three receptors, here GIPR, GLP-1R and GCGR. |
| GCGR | The glucagon receptor, expressed mainly in the liver. |
| C20 fatty diacid | A 20-carbon lipid side chain that binds albumin and extends half-life. |
| RUO | Research Use Only: sold for laboratory research, not for human or veterinary use. |
Frequently Asked Questions
What is the difference between GLP-2 and GLP-3 peptides?
Is GLP-3 RT stronger than GLP-2 TRZ?
Is GLP-2 TRZ the same as tirzepatide?
Is GLP-3 RT the same as retatrutide?
What is the half-life of GLP-3 RT vs GLP-2 TRZ?
Which is cheaper per mg, GLP-3 RT or GLP-2 TRZ?
Is retatrutide FDA-approved?
What molecular weight should a GLP-3 RT or GLP-2 TRZ COA show?
Can you use GLP-3 RT and GLP-2 TRZ in the same study?
Are GLP-3 RT and GLP-2 TRZ for human use?
Sources
- ClinicalTrials.gov NCT05929066 — Retatrutide (LY3437943) in participants with obesity or overweight (TRIUMPH program).
- ClinicalTrials.gov NCT06383390 — TRIUMPH-Outcomes: retatrutide cardiovascular and kidney outcomes, active.
- ClinicalTrials.gov NCT05929079 — Retatrutide in type 2 diabetes with obesity or overweight, completed 2026.
- Evo Peptides COA library — lot RT0006 and TRZ0001 results, evopeptidesus.com/coas.