What Did the NEJM Report on Retatrutide's Phase 3 Sleep Apnea Trials Show?
TL;DR: NEJM published Lilly's two Phase 3 retatrutide sleep-apnea trials (TRIUMPH-1/2-OSA). Retatrutide remains investigational and unapproved anywhere.
What Are the TRIUMPH-1-OSA and TRIUMPH-2-OSA Trials?
Two Phase 3 sub-studies of Eli Lilly's TRIUMPH programme were reported in the New England Journal of Medicine in a paper titled "Retatrutide Once Weekly for Treatment of Obstructive Sleep Apnea", presented at SleepEurope 2026.[1][2] TRIUMPH-1-OSA enrolled adults with obstructive sleep apnea (OSA) and obesity or overweight; TRIUMPH-2-OSA enrolled the same population with type 2 diabetes. The journal lists them as NCT05929066 and NCT05929079 and as sponsored by Lilly.[3]
Retatrutide is a GLP-1 / GIP / glucagon triple-agonist peptide under development by Lilly; see our mechanism of action guide for the receptor pharmacology. It is not approved by the MHRA, the FDA or any other regulator, and this guide describes a sponsor's trial reporting, not a use. Velox Peptides lists retatrutide only as a research reagent: retatrutide product page.
What Was Measured, and What Is the Apnea-Hypopnea Index?
The primary outcome in both trials was the change in the apnea-hypopnea index (AHI): the count of apnea and hypopnea events per hour of sleep on polysomnography, compared with placebo.[2] It is a physiological scoring measure rather than a symptom scale, which is why the way it is analysed matters. NEJM's summary states that retatrutide produced significantly greater AHI decreases than placebo; secondary-source coverage says the most common adverse events were gastrointestinal, but complete safety tables are in the full paper and supplement rather than the public abstract.[2][4]
Lilly's own press release, issued with its wider TRIUMPH update, frames the OSA results in terms of the largest observed AHI reduction (up to 36.1 events per hour, 60.6%, from a baseline of 58.6 events per hour in participants with moderate-to-severe OSA).[5] That is a sponsor headline, and it should be read alongside the journal's own analyses below.
Why Do Reported AHI Figures Differ Between Sources?
Clinical-trial reports increasingly state an estimand: precisely which effect is being estimated when participants stop treatment, switch therapy or miss visits. The reports on these trials describe two:
| Estimand | Where it appears | How to read it |
|---|---|---|
| Hybrid-treatment | Lilly press release; headline figures in trade coverage | Estimates the effect among participants while on treatment, handling post-discontinuation data differently; usually yields larger differences |
| Intention-to-treat (ITT) | NEJM paper, per secondary summaries | Analyses participants as randomised regardless of adherence; usually yields smaller differences from placebo |
Search-indexed summaries of the NEJM text report ITT placebo differences that are clearly smaller than the hybrid figures, and note that not every arm reached statistical significance under ITT.[4] We could not reach the full text from our publishing environment, so researchers should take exact values only from the NEJM article and its appendix. The methodological point stands regardless of the numbers: a headline figure and a regulator-facing figure can both be correct and still differ.
What Do These Trials Not Establish?
Several limits apply to any reading of the papers:
Investigational status
Neither trial is a licensing decision. Lilly's stated plan is an FDA submission in Q1 2027, and no regulator has approved retatrutide.[6]
Sponsor-funded design
Both trials were funded by Lilly. Independent replication and long-term follow-up are separate questions, as is any cardiovascular outcome evidence; analysts have noted that TRIUMPH-3 did not address major cardiovascular events.[7]
A single endpoint family
AHI captures breathing-event frequency under study conditions. It does not by itself describe broader clinical outcomes, and secondary analyses sit in the appendix.
Not a research-reagent result
These are clinical data from a pharmaceutical formulation made under licensed manufacturing and supervised protocols. They say nothing about laboratory-grade material.
How Does This Fit With the Rest of the Retatrutide Record?
The OSA paper is one strand of a wider Phase 3 programme. The main obesity results are covered in our TRIUMPH-1 NEJM guide and the diabetes-population data in the TRIUMPH-2 Lancet guide. For a dated map of what is peer-reviewed versus sponsor-only, see the evidence status guide, and for the earlier sleep-apnea background see retatrutide and sleep apnea. Lilly reports third-quarter results on 29 October 2026, covered in our earnings checkpoint.
How Should Researchers Separate Pharma Trial Data From Research Reagents?
Keep three categories apart. Licensed pharmaceutical development is Lilly's trials and filings. Regulatory and legal process is the FDA, the MHRA and the courts. Research-use compounds are reagents handled in vitro under a supplier's certificate of analysis. A publication in the first category does not alter the other two. For reagent work, the practical safeguards are batch-specific HPLC and mass-spectrometry data; see how to read a certificate of analysis.
Retatrutide is supplied by Velox Peptides as a research reagent only. It is not a medicine and has not been evaluated by the MHRA or FDA. Not for human or veterinary use. See our Research Use Policy and MHRA Statement.
References
- Retatrutide Once Weekly for Treatment of Obstructive Sleep Apnea. N Engl J Med, 2026 (TRIUMPH-1-OSA and TRIUMPH-2-OSA). nejm.org
- NEJM. Post on SleepEurope 2026 presentation of the TRIUMPH-1-OSA and TRIUMPH-2-OSA results. October 2026. x.com/NEJM
- ClinicalTrials.gov registrations NCT05929066 and NCT05929079, as listed by NEJM. clinicaltrials.gov
- HCPLive. "Retatrutide Improves Weight Loss, Knee Osteoarthritis Pain, Sleep Apnea Versus Placebo." 2026. hcplive.com
- Eli Lilly and Company. Press release on TRIUMPH weight, A1C, knee osteoarthritis pain and obstructive sleep apnea results (via PR Newswire). prnewswire.com
- Eli Lilly and Company. Q2 2026 financial results (Form 8-K), 5 August 2026. sec.gov
- Yahoo Finance. "Eli Lilly Reports Earnings on Oct. 29. Here's Why the Retatrutide Story Matters More Than the Quarter." October 2026. finance.yahoo.com
Frequently Asked Questions
What are TRIUMPH-1-OSA and TRIUMPH-2-OSA?
They are two Phase 3 sub-studies in Eli Lilly's TRIUMPH programme, run in adults with obstructive sleep apnea and obesity or overweight, without (TRIUMPH-1) or with (TRIUMPH-2) type 2 diabetes. They are registered as NCT05929066 and NCT05929079 and were funded by Lilly, per the NEJM listing.
What was the primary endpoint?
The change in the apnea-hypopnea index (AHI), the number of breathing-pause events per hour of sleep recorded in a sleep study, compared with placebo. Full secondary endpoints and safety tables are in the NEJM article and its supplementary appendix.
Why do different reports quote different AHI numbers?
Because trials can report outcomes under different estimands. Lilly's press release highlights a hybrid-treatment estimand, while the NEJM paper also reports an intention-to-treat analysis, which gives smaller differences from placebo. Neither is wrong, but they answer different questions.
Is retatrutide approved for sleep apnea?
No. As of 22 October 2026 retatrutide is investigational. Lilly has said it plans to file a Biologics License Application with the FDA in the first quarter of 2027, and no regulator has approved it for any indication.
Does this publication change the status of research-grade retatrutide?
No. A journal article on a licensed pharmaceutical developer's clinical trial does not change the Research Use Policy or the UK regulatory position. Velox Peptides supplies retatrutide solely as an in vitro research reagent.