Mazdutide vs Retatrutide
Mazdutide (LY3305677, also IBI362) and Retatrutide (LY3437943) were both discovered by Lilly and both activate the glucagon receptor, which sets them apart from semaglutide and tirzepatide. Mazdutide is a dual GLP-1 and glucagon receptor agonist; Retatrutide adds the GIP receptor to make a triple agonist. This page compares them as research compounds.
| Mazdutide | Retatrutide | |
|---|---|---|
| Development code | LY3305677 (IBI362) | LY3437943 |
| Developer | Discovered by Lilly; Innovent develops it in China | Eli Lilly |
| Receptor targets | GLP-1 and glucagon (dual) | GLP-1, GIP and glucagon (triple) |
| Molecule | Oxyntomodulin analogue | Single-peptide triple agonist |
| Administration in trials | Once weekly subcutaneous | Once weekly subcutaneous |
| Phase 3 obesity result | GLORY-1: 11.0% (4mg) and 14.0% (6mg) at 48 weeks, placebo +0.3% | TRIUMPH-1: 17.6% to 25.0% at 80 weeks, placebo 3.9% |
| Status | Approved in China in 2025 | Phase 3; Lilly plans a US filing in early 2027 |
| Peptx availability | UK single vials (10mg) and Factory Direct kits | UK single vials and Factory Direct kits |
- Development code
- LY3305677 (IBI362)LY3437943
- Developer
- Discovered by Lilly; Innovent develops it in ChinaEli Lilly
- Receptor targets
- GLP-1 and glucagon (dual)GLP-1, GIP and glucagon (triple)
- Molecule
- Oxyntomodulin analogueSingle-peptide triple agonist
- Administration in trials
- Once weekly subcutaneousOnce weekly subcutaneous
- Phase 3 obesity result
- GLORY-1: 11.0% (4mg) and 14.0% (6mg) at 48 weeks, placebo +0.3%TRIUMPH-1: 17.6% to 25.0% at 80 weeks, placebo 3.9%
- Status
- Approved in China in 2025Phase 3; Lilly plans a US filing in early 2027
- Peptx availability
- UK single vials (10mg) and Factory Direct kitsUK single vials and Factory Direct kits
Glucagon is the shared idea
Both molecules pair GLP-1 receptor activity with glucagon receptor activity. In animal studies glucagon signalling raises energy expenditure and drives fat breakdown in the liver, while the GLP-1 arm offsets glucagon's tendency to raise blood glucose. Retatrutide adds a third target, the GIP receptor, which it shares with tirzepatide.
Innovent describes mazdutide as an oxyntomodulin analogue: oxyntomodulin is the gut hormone that naturally activates both the GLP-1 and glucagon receptors. Retatrutide is a single engineered peptide built to activate all three receptors.
What the Phase 3 trials show
Mazdutide's GLORY-1 trial, published in the New England Journal of Medicine in 2025, enrolled 610 Chinese adults with overweight or obesity. At 48 weeks body weight fell 11.0% on 4mg and 14.0% on 6mg, against a 0.3% gain on placebo. A higher 9mg dose in GLORY-2, published in JAMA in 2026, reached 16.7% at 60 weeks against 1.5% on placebo.
Retatrutide's TRIUMPH-1 trial, published in the New England Journal of Medicine in September 2026, enrolled 2,339 adults in several countries, including the UK. At 80 weeks body weight fell 17.6%, 23.7% and 25.0% on 4mg, 9mg and 12mg, against 3.9% on placebo.
The programmes differ in population, BMI thresholds and length, so the figures are not a head-to-head comparison, and no trial has tested the two against each other.
Liver fat
Both compounds have reported large falls in liver fat. In GLORY-1, participants who started with at least 10% liver fat saw it fall by 65.9% on 4mg and 80.2% on 6mg at 48 weeks, against 5.3% on placebo, according to Innovent. In a 24-week retatrutide sub-study published in Nature Medicine in 2024, liver fat fell 82.4% on 12mg.
Bottom line for research labs
Mazdutide and Retatrutide are the two glucagon-containing compounds researchers compare most. Retatrutide has the larger Phase 3 dataset and the bigger reported effect. Mazdutide is the dual-agonist reference, with a growing record in diabetes and liver-fat research. Labs studying what the GIP arm adds often work with both.