Retatrutide and Obstructive Sleep Apnea: TRIUMPH-1 Phase 3 Subgroup Data (ADA 2026)

What did TRIUMPH-1 report about obstructive sleep apnea?

On 6 June 2026, Eli Lilly presented the full dataset from the TRIUMPH-1 Phase 3 trial at the 86th American Diabetes Association Scientific Sessions in New Orleans. Among the pre-specified secondary endpoint analyses was a subgroup examining retatrutide's effect on obstructive sleep apnea (OSA) — one of the most prevalent obesity-associated comorbidities and a growing focus in incretin receptor pharmacology research following tirzepatide's SURMOUNT-OSA results.[1]

TRIUMPH-1 enrolled 2,339 adults with obesity (BMI ≥30 kg/m²) or overweight (BMI ≥27 kg/m²) plus at least one weight-related comorbidity, with no type 2 diabetes. Participants were randomised 1:1:1:1 to once-weekly subcutaneous retatrutide (4, 9, or 12 mg) or placebo and followed for 80 weeks. Full primary and secondary endpoint data — including the OSA subgroup — were presented at ADA 2026 alongside a simultaneous announcement of TRANSCEND-T2D-1, Eli Lilly's companion Phase 3 trial in type 2 diabetes.[2]

Retatrutide (LY3437943, CAS 2381089-83-2) is a synthetic acylated peptide that simultaneously activates GLP-1, GIP, and glucagon receptors — extending the incretin receptor hypothesis beyond the dual-agonist model of tirzepatide. For the full mechanism of action, preclinical pharmacology, and primary TRIUMPH-1 weight outcomes, see the Retatrutide Research Overview. For the TRANSCEND-T2D-1 Phase 3 data in type 2 diabetes published simultaneously in The Lancet, see the Type 2 Diabetes guide. Velox Peptides supplies retatrutide as an HPLC-verified (≥99% purity) lyophilised reagent for in vitro research use only. View the product page →

Why is the GLP-1/glucagon class of interest in OSA research?

Obstructive sleep apnea is characterised by recurrent upper-airway collapse during sleep, quantified by the apnea–hypopnea index (AHI) — a count of complete and partial breathing pauses per hour measured by polysomnography. Mechanistic pathways linking metabolic pharmacology to OSA include adipose deposition in pharyngeal tissue, altered respiratory drive, and reduced genioglossal muscle tone at higher adiposity levels — all of which are of interest to researchers studying incretin receptor biology in obesity models.[3]

Within the incretin class, prior Phase 3 evidence from tirzepatide (a dual GLP-1/GIP agonist) demonstrated significant AHI reduction in the SURMOUNT-OSA trial published in the New England Journal of Medicine in June 2024 (Malhotra et al.; PMID 38934533), which led to FDA approval of tirzepatide for obesity-related moderate-to-severe OSA. Retatrutide extends this model by adding glucagon receptor agonism — a receptor expressed in the central nervous system and implicated in both appetite regulation and cardiorespiratory signalling in preclinical literature. Whether glucagon receptor co-activation contributes independently to upper-airway outcomes, or whether TRIUMPH-1's OSA findings are attributable primarily to the magnitude of weight loss, remains an open question at the basic research level.[4]

The TRIUMPH-1 OSA subgroup provides the first large-scale Phase 3 dataset linking a GLP-1/GIP/glucagon triple agonist to polysomnographic outcomes — a reference dataset for researchers working at the interface of incretin pharmacology and sleep-disordered breathing biology.

What were the apnea-hypopnea index reduction figures?

The TRIUMPH-1 OSA subgroup analysis included participants who at baseline had moderate-to-severe obstructive sleep apnea. The mean baseline AHI in this subgroup was approximately 58.6 events per hour — a level classified as severe by standard polysomnographic criteria (AHI ≥30 = severe). At week 80, the 12 mg dose of retatrutide was associated with an AHI reduction of 36.1 events per hour, representing a 60.6% reduction from baseline.[1]

An AHI reduction from ~58.6 to ~22.5 events per hour (the approximate post-treatment value implied by the published absolute and percentage figures) would represent a shift from the severe OSA stratum toward the moderate OSA stratum under standard polysomnographic classification (AHI 15–29.9 = moderate; AHI ≥30 = severe). Researchers modelling incretin-class effects on respiratory physiology will note that this degree of AHI improvement is broadly consistent with the magnitude of weight loss observed in the main TRIUMPH-1 analysis (28.3% at 12 mg, 80 weeks), given established correlations in the observational and interventional sleep-medicine literature between percentage weight reduction and AHI change.

How do the retatrutide and tirzepatide OSA Phase 3 datasets compare?

Tirzepatide became the first GLP-1-class compound to obtain a dedicated FDA indication for obesity-related moderate-to-severe OSA in adults, based on the SURMOUNT-OSA Phase 3 programme published in the New England Journal of Medicine by Malhotra et al. (June 2024; PMID 38934533). This established the first regulatory-grade dataset on polysomnographic outcomes for an incretin agonist, making TRIUMPH-1 the natural methodological successor for researchers studying triple-receptor pharmacology.[5]

Direct numerical comparison of effect sizes is methodologically limited by differences in population selection, baseline AHI severity, trial duration, outcome measurement protocols, and study design (dedicated OSA trial vs pre-specified subgroup). The table below contextualises published design parameters for research reference only; it should not be read as a head-to-head clinical comparison.

Tirzepatide figures are drawn from the SURMOUNT-OSA publication (Malhotra et al., NEJM 2024; PMID 38934533). The two trials are separate studies with different primary designs; effect-size differences may reflect the additional 28 weeks of treatment in TRIUMPH-1, higher absolute baseline AHI in the retatrutide subgroup, different patient selection criteria, and the greater degree of weight loss achieved over 80 weeks compared with 52 weeks. Researchers interested in the potential mechanistic contribution of glucagon receptor agonism to upper-airway outcomes will note that isolating this from weight-mediated effects requires specifically designed experiments beyond what Phase 3 subgroup analyses can demonstrate.[4]

What other TRIUMPH-1 findings were presented at ADA 2026?

The ADA 2026 TRIUMPH-1 data package covered a broad range of obesity-complication outcomes alongside the OSA subgroup. These are summarised here for researchers studying multi-system incretin pharmacology; all figures refer to the 12 mg dose at 80 weeks unless otherwise noted, and are sourced from Eli Lilly press materials dated 6 June 2026.[1][2]

Primary weight outcome

Mean body-weight reduction of 28.3% (approximately 70.3 lbs / 31.9 kg) at week 80 with the 12 mg dose; 65.3% of participants achieved a BMI below 30 kg/m². At a 104-week extension, participants with a starting BMI ≥35 who continued on 12 mg reached up to 30.3% weight reduction.

Cardiometabolic markers at 80 weeks

Knee osteoarthritis pain (TRIUMPH-4)

A separate TRIUMPH sub-trial (TRIUMPH-4), also presented at ADA 2026, enrolled participants with obesity and knee osteoarthritis. At 68 weeks, retatrutide 12 mg was associated with a 73.1% reduction in WOMAC pain subscale score and mean body-weight loss of 28.7%. Additionally, the trial reported a 75.8% reversal rate of prediabetes to normoglycemia and approximately 20% reductions in LDL cholesterol.[1]

Taken together, the June 6 ADA 2026 data release characterised retatrutide as a compound with a broad multi-system signal in clinical research, spanning respiratory (OSA), musculoskeletal (osteoarthritis), and cardiometabolic endpoints alongside the primary weight endpoint. For researchers studying multi-receptor incretin pharmacology, this dataset provides a uniquely comprehensive picture of how simultaneous GLP-1R, GIPR, and glucagon receptor co-activation correlates with multi-system outcomes in a large Phase 3 population.

Where do OSA findings fit in the broader TRIUMPH programme?

The TRIUMPH (TRIple-hormone-receptor aGonist for ObesIty Management Pivotal) programme comprises eight pivotal Phase 3 trials enrolling more than 5,800 participants across weight-management and diabetes indications, plus a separate cardiovascular outcomes trial enrolling approximately 10,000 patients. The OSA findings emerged as a pre-specified subgroup within TRIUMPH-1 rather than from a dedicated OSA trial — a distinct structure from tirzepatide's SURMOUNT-OSA, which used polysomnographic AHI as its primary endpoint.[6]

Whether Eli Lilly pursues a standalone retatrutide OSA regulatory indication (as it did for tirzepatide via SURMOUNT-OSA) has not been publicly announced as of June 2026. A dedicated OSA NDA would likely require a pivotal trial with polysomnographic outcomes as the primary endpoint. Researchers tracking the regulatory evolution of triple-receptor agonism in sleep-disordered breathing should monitor TRIUMPH programme expansion announcements expected later in 2026.[2]

Remaining TRIUMPH readouts expected later in 2026 include TRIUMPH-2 (obesity/overweight with T2D) and TRIUMPH-3 (obesity with established cardiovascular disease). Combined with TRIUMPH-1 (reported May–June 2026) and TRANSCEND-T2D-1 (published in The Lancet, June 2026 — see the T2D guide), the publicly available Phase 3 dataset for retatrutide will span four trials when these read out. Eli Lilly has indicated an NDA submission to the FDA is targeted for Q4 2026 across the obesity and diabetes indications.

Velox Peptides Supply Information

Retatrutide is supplied 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.

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