Sally is a 70-year-old female who has been diagnosed with type 2 diabetes ten years ago and has been working hard to self-manage her diabetes through lifestyle and medications (semaglutide, insulin glargine, empagliflozin, metformin). She survived a myocardial infarction a year ago. She also has stage 3b CKD, osteoarthritis of the knee and obesity with a BMI of 30. During Sally’s most recent office visit, she asked her provider about a novel triple incretin agonist that’s being studied for obesity and diabetes as she is interested in additional weight loss benefits. Sally asked, “How is this triple incretin agonist different from semaglutide, and could it possibly help me in other ways too?”
Retatrutide is a triple agonist in that it is a receptor agonist of the glucose dependent insulinotrophic polypeptide (GIP), glucagon-like peptide 1(GLP-1) and glucagon receptors. The potential mechanisms of action of retatrutide in obesity are maintaining energy expenditure, improved glucose, insulin and lipid metabolism, reduced inflammatory markers, and improved appetite regulation. How exactly does this mechanism of action differ from tirzepatide and semaglutide? Tirzepatide is a dual agonist that targets the GIP and GLP-1 receptors while semaglutide targets the GLP-1 receptor. Retatrutide’s advantage is that it also targets the glucagon receptor.
Retatrutide is currently being studied in persons with type 2 diabetes (TRANSCEND phase 3 clinical trial program), obesity (TRIUMPH phase 3 clinical trial programs) and with a substudy assessing benefit in metabolic dysfunction-associated steatotic liver disease. The results from these trials are promising.
TABLE 1. Select Phase 2 Trials
| Trial Name | Population | Key Inclusion Criteria | Duration of Study | Primary Outcome | Results |
| Phase 2 Obesity Trial (1) | Obesity | Adults 18 – 75 years of ageBMI ≥ 30 and ≤ 50 kg/m2, or ≥ 27 to < 30 kg/m2 with at least one of the following:Hypertension -Dyslipidemia -CVD | 48 weeks | Percentage change in weight from baseline to 24 weeks | −7.2% (1-mg group)−11.8% (4-mg group with an initial dose of 2 mg)−13.9% (4-mg group with an initial dose of 4 mg)−16.7% (8-mg group with an initial dose of 2 mg)−17.9% (8-mg group with an initial dose of 4 mg)−17.5% (12-mg group with an initial dose of 2 mg)−1.6% (placebo group) |
| A Substudy of Phase 2 Trial in Participants with Obesity without Diabetes (2) | Metabolic Dysfunction-Associated Steatotic Liver Disease | Metabolic dysfunction-associated steatotic liver disease ≥10% of liver fat | 48 weeks | Mean relative change from baseline in liver fat (LF) from baseline to at 24 weeks | -42.9% (1 mg group)-57.0% (4 mg group)-81.4% (8 mg group)-82.4% (12 mg group) +0.3% (placebo group) |
Table 2. Overview of TRIUMPH Phase 3 Clinical Trial Program (in persons with obesity) (with focus on trials of retatrutide vs. placebo)
| Trial Name | Population | Key Inclusion Criteria | Duration of Study | Primary Outcome |
| TRIUMPH-1 (3) | Adults with Overweight or Obesity | BMI ≥ 30 kg/m2 OR BMI ≤ 27 with ≥ 1 body weight related comorbidity (a) without T2D | 80 weeks | Percent change in body weight from baseline |
| TRIUMPH-2 (4) | Adults with T2D and Overweight or Obesity | BMI ≥ 27 T2D | 80 weeks | Percent change in body weight from baseline |
| TRIUMPH-3 (5) | Adults with Obesity and CV Disease | BMI ≥ 35Established CV disease with ≥ 1 of the following:Prior ischemic or hemorrhagic stroke,Prior MI, or Symptomatic PAD | 80 weeks | Percent change in body weight from baseline |
| TRIUMPH-4 (6) | Adults with Overweight or Obesity with Knee Osteoarthritis | BMI ≥ 27Index knee pain for > 12 weeks prior to screening and for > 15 days over previous monthKnee x-ray with moderate radiographic changesMeets ACR criteria (clinical and radiological) for OA | 68 weeks | Percent change in body weight from baselineChange from baseline in WOMAC Pain Subscale Score |
| TRIUMPH-6 (7) | Adults with obesity | BMI ≥ 30 kg/m2 | 116 weeks | Percent change in body weight from baseline |
| TRIUMPH-OUTCOMES (8) | People with Obesity and ASCVD and/or CKD | BMI ≥ 27With or without T2D (A1c ≤ 10%)Established ASCVD and/or CKD | 248 weeks | Time to first occurrence of composite endpointsTime to first occurrence of composite endpoint of ESKD, >/= 40% sustained decline in eGFR, CV death or renal death |
All studies are retatrutide versus placebo.
(a) Comorbidities include CV disease, dyslipidemia, hypertension or obstructive sleep apnea
What about side effects and cost? Based on the mechanism of action, the side effects will be similar to tirzepatide and semaglutide, particularly the gastrointestinal related in nature. Cost is not available – however, it is reasonable to anticipate it will be similar to tirzepatide and semaglutide.
Back to Sally, retatrutide may benefit her over the semaglutide she is currently taking. While there is not a head-to-head comparison of retatrutide vs. semaglutide, the triple action of retatrutide should result in more weight loss and better hemoglobin A1c reduction while possibly also reducing cardiovascular risk. Sally feels this medication might be an option for her in the future after FDA approval. She is excited to know that new novel medications are being developed that can address multiple chronic conditions with one medication.
References:
- Jastreboff AM, Kaplan LM, Frias JP, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity – A Phase 2 Trial. New England Journal of Medicine. 2023;389(6):514-25. doi:10.1056/NEJMoa2301972
- Sanyal AJ, Kaplan LM, Frias JP, et al. Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial. Nat Med. 2024;30(7):2037-2048. doi:10.1038/s41591-024-03018-2
- A study of retatrutide (LY3437943) in participants who have obesity or overweight (TRIUMPH-1). ClinicalTrials.gov identifier: NCT05929066. Updated April 18, 2025. September 2, 2025. https://clinicaltrials.gov/study/NCT05929066
- A study of retatrutide (LY3437943) in participants with type 2 diabetes mellitus who have obesity or overweight (TRIUMPH-2). Clinicaltrials.gov identifier: NCT05929079. Updated April 18, 2025. Accessed September 2, 2025. https://clinicaltrials.gov/study/NCT05929079
- A study of retatrutide (LY3437943) in participants with obesity and cardiovascular disease (TRIUMPH-3). Clinicaltrials.gov identifier: NCT05882045. Updated July 23, 2025. Accessed September 2, 2025. https://clinicaltrials.gov/study/NCT05882045
- A study of retatrutide (LY3437943) once weekly in participants who have obesity or overweight and osteoarthritis of the knee (TRIUMPH-4). Clinicaltrials.gov identifier: NCT05931367. Updated April 22, 2025. Accessed September 2, 2025. https://clinicaltrials.gov/study/NCT05931367
- A Study of Retatrutide (LY3437943) in the Maintenance of Weight Reduction in Individuals With Obesity (TRIUMPH-6). Clinicaltrials.gov identifier: NCT06859268. Updated August 27, 2025. Accessed September 4, 2025. https://clinicaltrials.gov/study/NCT06859268.
- The effect of retatrutide once weekly on cardiovascular outcomes and kidney outcomes in adults living with obesity (TRIUMPH-Outcomes). Clinicaltrials.gov identifier: NCT06383390. Updated September 8, 2025. Accessed September 11, 2025. https://clinicaltrials.gov/study/NCT06383390













