What is ?
(LY3437943) is a novel triple hormone receptor agonist developed by Eli Lilly and currently in Phase 3 clinical trials. It simultaneously activates three receptors: GLP-1 (glucagon-like peptide-1), GIP (glucose-dependent insulinotropic polypeptide), and glucagon receptors. This triple mechanism sets it apart from every other GLP-1 class compound currently available — including (single agonist) and (dual agonist).
In Phase 2 clinical trials published in the New England Journal of Medicine (2023), participants receiving the highest dose of (12mg weekly) achieved a mean weight loss of 24.2% over 48 weeks. For context, achieves approximately 15% and approximately 20-22%. represents a meaningful step forward in the GLP-1 class.
The key number: 24.2% average body weight reduction in Phase 2 trials at 48 weeks. This is the highest weight reduction figure recorded for any pharmaceutical compound in the GLP-1 class to date.
Triple Agonist Mechanism — Why It Works Differently
Understanding why outperforms its predecessors requires understanding what each receptor does:
- GLP-1 receptor: Slows gastric emptying, reduces appetite, improves insulin secretion, reduces glucagon. This is the primary mechanism behind and .
- GIP receptor: Enhances insulin secretion in a glucose-dependent manner, may improve GLP-1 receptor sensitivity, and has shown effects on adipose tissue. adds this to GLP-1.
- Glucagon receptor: This is what's new in . Glucagon increases energy expenditure and promotes fat oxidation in the liver (lipolysis). Adding glucagon agonism creates an additional energy expenditure pathway that neither nor activates.
The result is a compound that reduces intake (GLP-1), enhances metabolic processing (GIP), and increases energy output (glucagon) simultaneously. That three-pronged approach explains the superior weight loss numbers in research.
vs vs : Honest Comparison
Here's where each compound stands based on current research:
- (/): GLP-1 single agonist. ~15% weight loss at 68 weeks (STEP trials). Most studied, longest track record. Weekly injection.
- (/Zepbound): GLP-1 + GIP dual agonist. ~20-22% weight loss at 72 weeks (SURMOUNT trials). Newer, fewer long-term studies but strong efficacy data.
- : GLP-1 + GIP + Glucagon triple agonist. ~24% weight loss at 48 weeks (Phase 2). Still in trials — no long-term cardiovascular outcome data yet. Highest efficacy figures of the three.
Bottom line: If efficacy is the primary research variable, the data currently favors . If you prioritize a longer established safety record, or have more data. Both are valid research considerations.
Research Findings
Key published findings on research as of 2026:
- Phase 2 weight loss trial (NEJM, 2023): 338 participants, dose-dependent weight loss ranging from 8.7% (1mg) to 24.2% (12mg) over 48 weeks. Statistically significant vs placebo across all doses.
- Liver fat reduction: Significant reductions in hepatic fat content observed across dosing groups — potentially relevant to MASLD (metabolic-associated steatotic liver disease) research.
- Metabolic markers: Improvements in fasting glucose, insulin resistance markers (HOMA-IR), triglycerides, and blood pressure compared to placebo.
- Phase 3 trials: Multiple ongoing trials as of 2026 including TRIUMPH-1 (obesity), TRIUMPH-2 (T2D), and TRIUMPH-3 (cardiovascular outcomes).
Dosing in Research Contexts
Research dosing protocols for typically follow an escalation schedule similar to other GLP-1 class compounds to minimize gastrointestinal side effects during the adjustment period:
- 5mg vials: Used in lower-dose initiation protocols
- 10mg vials: Mid-range dosing
- 15mg and 20mg vials: Higher dose protocols
- 30mg vials: Extended research protocols
Most research protocols involve weekly subcutaneous administration. Gradual dose escalation is standard to assess tolerance before increasing.
Bacteriostatic water is required for reconstitution. Always use fresh bacteriostatic water and store reconstituted peptides refrigerated. See our complete reconstitution guide.
Side Effects Observed in Research
Like all GLP-1 class compounds, research shows a characteristic side effect profile:
- Most common (>10% in trials): Nausea, vomiting, diarrhea, constipation, decreased appetite. These are dose-dependent and typically most pronounced during dose escalation.
- GI side effects generally diminish after 4-8 weeks as subjects adjust to the compound.
- Heart rate: Modest increases in heart rate observed (consistent with GLP-1 class effects).
- Hypoglycemia: Rare when used as monotherapy due to glucose-dependent mechanism, but relevant when combined with insulin or sulfonylureas in research.
Where to Buy for Research
This is where sourcing matters enormously. Most on the market is manufactured overseas — often in Chinese chemical facilities with inconsistent quality control and no GMP standards. We've tested multiple sources and the variance in reconstitution quality and stability is significant.
The one vendor we consistently recommend for is UNYX Peptides. They're one of the only US-based suppliers manufacturing domestically at a GMP-certified facility in Arizona. That matters for purity, consistency, and reliability in research settings.
- 100% USA-manufactured — GMP-certified Arizona facility (not imported from overseas)
- Third-party tested for purity — among the purest available in the US market
- Full catalog: GLP-1s, healing peptides, nootropics, longevity compounds
- Ships same or next business day — fastest fulfillment we've tested
- Bacteriostatic water in stock
- Subscribe & save on all products