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Who Was Studied in Retatrutide Trials? Populations and Eligibility Criteria

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PBIPeptide Bio Index Editorial DeskSource-labeled research summary
Source-limited8 min readUpdated Sep 8, 2026
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  1. What retatrutide is and the trials covered
  2. Participants and eligibility in the Phase 2 randomized trial (NEJM report)
  3. Populations and design elements in the Phase 3 TRIUMPH registrational program
  4. Participants and eligibility in the TRANSCEND-T2D-1 Phase 3 trial (type 2 diabetes)
  5. Common inclusion thresholds reported across sources
  6. What the reviewed sources do not fully report about eligibility and participant characteristics
  7. Reported study-design details from cited sources
  8. Limitations and research gaps
  9. Documentation checklist
  10. Related research supplies
  11. More Retatrutide research
  12. Sources and references

Disclosure: Peptide Bio Index is affiliated with SourcePoint Research and may earn from qualifying purchases or affiliate links.

This article summarizes published research and reported study designs. It is not medical advice, dosing guidance, or a personal-use recommendation.

Source-limited research note: The reviewed sources were incomplete, ambiguous, or insufficient for a normal article. This page labels missing details rather than guessing.

This deep dive summarizes who was enrolled in reported retatrutide trials and the main eligibility thresholds described in the reviewed sources. It focuses on trial populations (age, body-mass index, metabolic criteria), sample sizes, and trial-design features relevant to interpreting generalizability of results.

What retatrutide is and the trials covered

Retatrutide (LY3437943) is described in the reviewed sources as a triple-receptor agonist activating GIP, GLP-1, and glucagon receptors; clinical development includes Phase 2 randomized trials and a Phase 3 registrational program (TRIUMPH) as well as disease-specific Phase 3 trials such as TRANSCEND-T2D-1 that enrolled people with type 2 diabetes. [S2] [S6] [S7]

Participants and eligibility in the Phase 2 randomized trial (NEJM report)

The Phase 2, double-blind, randomized, placebo-controlled trial enrolled 338 adults and targeted people with obesity defined as BMI ≥30 kg/m2 or BMI 27 to <30 kg/m2 plus at least one weight-related condition; participants were randomized to multiple retatrutide dose arms or placebo and received once-weekly subcutaneous injections for a 48-week treatment period, with the primary end point at 24 weeks. [S2]

The randomized sample was 51.8% male; dose groups included 1 mg, multiple 4-mg and 8-mg arms (with different starting-dose strategies), and 12 mg, with a complex 2:1:1:1:1:2:2 allocation ratio described in the report. [S2]

Populations and design elements in the Phase 3 TRIUMPH registrational program

The TRIUMPH program consists of four Phase 3, multicenter, randomized, double-blind trials that evaluate weekly subcutaneous retatrutide versus placebo in conjunction with healthy diet and physical activity; the program is designed as a basket of weight-management trials and nested studies for obstructive sleep apnoea and knee osteoarthritis and plans to recruit over 5,800 participants across these studies. [S6]

TRIUMPH includes two weight-management basket trials (TRIUMPH-1 and TRIUMPH-2) with OSA and/or knee OA protocols nested within the weight-management trial, one weight-management trial in a population with cardiovascular disease (TRIUMPH-3), and a stand-alone OA trial (TRIUMPH-4); primary endpoints vary by subtrial (percent change in body weight for weight management, Apnea–Hypopnea Index for OSA, and WOMAC pain subscale for knee OA). [S6]

Participants and eligibility in the TRANSCEND-T2D-1 Phase 3 trial (type 2 diabetes)

TRANSCEND-T2D-1 enrolled adults aged ≥18 years with type 2 diabetes inadequately controlled by diet and exercise, requiring baseline HbA1c between 7.0% and 9.5% (53–80 mmol/mol) and a BMI of at least 23 kg/m2; 537 participants were randomized across retatrutide 4 mg, 9 mg, 12 mg, and placebo arms in a 1:1:1:1 allocation and treated once weekly for 40 weeks. [S7]

Baseline characteristics reported in the source excerpt include mean age 48.8 years, mean HbA1c 7.9%, mean duration of diabetes 2.5 years, mean BMI 35.8 kg/m2, and an overall randomised sample of 296 female (55%) and 241 male (45%) participants. [S7]

Common inclusion thresholds reported across sources

Reported inclusion thresholds across the reviewed trial excerpts include age ≥18 years (explicit in TRANSCEND-T2D-1), BMI-based cutoffs for weight-management trials (Phase 2 used BMI ≥30 or BMI 27–<30 plus a weight-related condition), and disease-specific criteria for nested cohorts (e.g., OSA and OA were explicitly targeted in TRIUMPH's nested protocols). [S2] [S7] [S6]

What the reviewed sources do not fully report about eligibility and participant characteristics

The reviewed excerpts do not provide complete details on many typical eligibility elements such as specific exclusion criteria, racial/ethnic breakdowns beyond aggregate sex distribution, precise definitions of the ‘weight-related conditions’ used for BMI 27–<30 inclusion, co-medication allowances, or the full set of baseline comorbidities and laboratory thresholds used to screen participants.

Dosing regimens for Phase 3 TRIUMPH trials (specific dose arms and starting-dose strategies), and certain trial operational details (e.g., exact treatment durations for each TRIUMPH substudy), are not reported in the reviewed excerpts.

Reported study-design details from cited sources

The following table summarizes protocol details reported in cited studies. These details are provided as literature context only and are not recommendations or instructions.

Source Study Type Model / Subject Amount Reported Route Reported Frequency Duration Notes
[S2] Phase II randomized, double-blind, placebo-controlled trial Adults with obesity (Phase 2 trial) Dose arms: 1 mg; 4 mg (initial dose 2 mg and initial dose 4 mg combined in reporting); 8 mg (initial dose 2 mg and initial dose 4 mg combined in reporting); 12 mg (initial dose 2 mg) Subcutaneous Once weekly 48 weeks 338 adults enrolled; randomization ratio 2:1:1:1:1:2:2 across multiple dose arms and placebo; primary endpoint percentage change in body weight at 24 weeks.
[S7] Phase III randomized, double-blind, placebo-controlled trial Adults with type 2 diabetes inadequately controlled by diet/exercise (TRANSCEND-T2D-1) 4 mg, 9 mg, 12 mg Subcutaneous Once weekly 40 weeks 537 participants randomized 1:1:1:1 to retatrutide 4 mg, 9 mg, 12 mg, or placebo; key inclusion: age ≥18 years, HbA1c 7.0–9.5%, BMI ≥23 kg/m2; primary endpoint change in HbA1c at week 40; key secondary: percent change in bodyweight at week 40.
[S6] Phase III registrational program (four multicenter randomized, double-blind trials; basket design) Adults with obesity and related complications (TRIUMPH registrational program) not reported in the reviewed source Subcutaneous Once weekly not reported in the reviewed source Program includes two weight-management basket trials with nested OSA and/or OA protocols (TRIUMPH-1 and TRIUMPH-2), one weight-management trial in participants with cardiovascular disease (TRIUMPH-3), and one stand-alone OA trial (TRIUMPH-4); planned enrollment across the program is over 5,800 participants; primary endpoints vary by subtrial (percent change in body weight for weight management, Apnea–Hypopnea Index for OSA, WOMAC pain subscale for OA).

Limitations and research gaps

  • This summary is limited to the reviewed source excerpts; full-text articles and trial-registry entries may contain additional eligibility and demographic details not captured here.
  • Key eligibility components commonly reported in full protocols (detailed exclusion criteria, concomitant-medication rules, race/ethnicity breakdown, renal/hepatic cutoffs) are not available in the provided excerpts.
  • Some program-level descriptions (TRIUMPH) are design-focused and do not include participant-level inclusion thresholds or dosing details in the reviewed excerpt.
  • Study populations reported in the excerpts reflect trial-specific enrollment and may not represent broader clinical populations or unselected real-world patients.

Documentation checklist

  • Locate the primary trial publications and trial-registry records (Phase 2 NEJM report NCT04881760 and Phase 3/registry publications) to confirm eligibility details.
  • Confirm BMI and metabolic thresholds reported for each trial before comparing populations across studies.
  • When extracting protocol details, separate inclusion criteria (age, BMI, HbA1c, comorbidities) from dosing and randomization details.
  • Note where the published excerpt omits key eligibility items (e.g., exclusion criteria, detailed comorbidity definitions) and consult full texts or registry entries if needed.
  • Record whether trials nested disease-specific cohorts (e.g., OSA, knee OA) within weight-management trials to avoid double-counting participants.
  • Trial master file binder and participant screening logs (documentation and eligibility tracking)
  • Site temperature-monitoring devices and refrigerated storage logs for investigational-product stability records
  • Sample labeling materials and compliant specimen transport containers for central laboratory samples
  • Surface cleaning wipes and clinic-grade disinfectant for study site environmental cleaning

Research organization supplies: Common tools used for research documentation workflows may include lab notebooks, label makers, sample storage boxes, inventory stickers, and temperature log sheets.

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More Retatrutide research

Sources and references

  1. [S1] Locatelli JC, Costa JG, Haynes A, Naylor LH, Fegan PG, Yeap BB. Incretin-Based Weight Loss Pharmacotherapy: Can Resistance Exercise Optimize Changes in Body Composition?. Diabetes care. 2024. PMID: 38687506. DOI: 10.2337/dci23-0100
  2. [S2] Jastreboff AM, Kaplan LM, Frías JP, Wu Q, Du Y, Gurbuz S. Triple-Hormone-Receptor Agonist Retatrutide for Obesity – A Phase 2 Trial.. The New England journal of medicine. 2023. PMID: 37366315. DOI: 10.1056/NEJMoa2301972
  3. [S3] Wang Y, Zhou Y, Wang Z, Ni Y, Prud'homme GJ, Wang Q. Efficacy of GLP-1-based Therapies on Metabolic Dysfunction-associated Steatotic Liver Disease and Metabolic Dysfunction-associated Steatohepatitis: A Systematic Review and Meta-analysis.. The Journal of clinical endocrinology and metabolism. 2025. PMID: 40489581. DOI: 10.1210/clinem/dgaf336
  4. [S4] Katsi V, Koutsopoulos G, Fragoulis C, Dimitriadis K, Tsioufis K. Retatrutide-A Game Changer in Obesity Pharmacotherapy.. Biomolecules. 2025. PMID: 40563436. DOI: 10.3390/biom15060796
  5. [S5] Drucker DJ. Efficacy and Safety of GLP-1 Medicines for Type 2 Diabetes and Obesity.. Diabetes care. 2024. PMID: 38843460. DOI: 10.2337/dci24-0003
  6. [S6] Giblin K, Kaplan LM, Somers VK, Le Roux CW, Hunter DJ, Wu Q. Retatrutide for the treatment of obesity, obstructive sleep apnea and knee osteoarthritis: Rationale and design of the TRIUMPH registrational clinical trials.. Diabetes, obesity & metabolism. 2026. PMID: 41090431. DOI: 10.1111/dom.70209
  7. [S7] Bajaj HS, Welch M, Shah P, Luna E, Jaouimaa FZ, Liu B. Efficacy and safety of retatrutide, a GIP, GLP-1, and glucagon receptor agonist, in people with type 2 diabetes and inadequate glycaemic control with diet and exercise (TRANSCEND-T2D-1): a double-blind, randomised, phase 3 trial.. Lancet (London, England). 2026. PMID: 42250575. DOI: 10.1016/S0140-6736(26)00967-0
  8. [S8] Wen J, Nadora D, Bernstein E, How-Volkman C, Truong A, Joy B. Evaluating the Rates of Pancreatitis and Pancreatic Cancer Among GLP-1 Receptor Agonists: A Systematic Review and Meta-Analysis of Randomised Controlled Trials.. Endocrinology, diabetes & metabolism. 2025. PMID: 40988099. DOI: 10.1002/edm2.70113

Peptide Bio Index is affiliated with SourcePoint Research. Articles may link to SourcePointResearch.com and third-party affiliate products. As an Amazon Associate, Peptide Bio Index earns from qualifying purchases. Content is educational and research-literature focused only and is not medical advice, dosing guidance, or a personal-use recommendation.

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