Retatrutide Provides Substantial Weight Loss in Patients With Obesity or Overweight

On May 21, 2026, Eli Lilly announced topline results from TRIUMPH-1, its phase 3 trial of retatrutide in adult patients with obesity or overweight with ≥1 weight-related comorbidity and without diabetes. At the 80 week endpoint of the trial, all doses of the GLP-1/GIP/glucagon triple agonist, including 4 mg, 9 mg, and 12 mg, saw major reductions in weight, with an average of 70.3 pounds lost across all 3 arms.1

Diabetes Dialogue cohosts Diana Isaacs, PharmD, and Natalie Bellini, DNP, discuss the implications of these significant data and speculate on the future of this promising new treatment for obesity.

Check out the full episode on the latest diabetes news here.

In this segment, Isaacs and Bellini frame the results as a major development in the rapidly evolving obesity treatment landscape, particularly as clinicians begin to move beyond single- and dual-incretin therapies toward more advanced multi-receptor approaches. Retatrutide is presented as a potential next-generation therapy capable of producing weight loss outcomes approaching those historically seen only with bariatric surgery.

The discussion emphasizes the study population and trial design, noting that participants did not have diabetes, an important distinction given that incretin-based therapies typically produce less weight reduction in patients with type 2 diabetes. Participants enrolled in the study had obesity or overweight accompanied by at least 1 obesity-related comorbidity, such as hypertension or hyperlipidemia. Isaacs and Bellini underscore the long-term nature of the trial, with primary endpoint analysis conducted at 80 weeks and extension data extending through 104 weeks, highlighting the importance of sustained treatment approaches for obesity as a chronic disease.

The speakers review the topline efficacy data across all 3 studied doses—4 mg, 9 mg, and 12 mg—stating that each dose met both primary and key secondary endpoints. Investigators reported average weight loss reaching 70.3 pounds, corresponding to a 28.3% reduction in body weight. Nearly half of participants, 45.3%, achieved at least 30% weight loss, results that the cohosts repeatedly compare to bariatric surgery outcomes. The extension-phase findings generated additional enthusiasm, particularly among participants with baseline BMI ≥35 kg/m², where average weight loss reportedly reached 85 pounds, or 30.3% of body weight, at 104 weeks. The speakers note that weight loss had not yet plateaued at the time of analysis, suggesting the possibility of additional reductions with longer follow-up.

Considerable attention is also given to tolerability and treatment adherence. The speakers highlight the unexpectedly favorable discontinuation data in the 4 mg arm, where discontinuation rates were reportedly lower than placebo. They characterize this as especially meaningful given the gastrointestinal adverse effects and adherence challenges commonly associated with GLP-1–based therapies. The simplified dosing structure, consisting of only 3 doses, is also described as a practical advantage for future clinical implementation.

The conversation then shifts toward the broader clinical implications of triple agonist therapies. Isaacs and Bellini outline upcoming studies within the broader TRIUMPH program, including trials evaluating retatrutide in obesity with type 2 diabetes and obesity with established cardiovascular disease. The speakers stress the importance of determining whether the profound weight reductions observed with triple agonism will also translate into cardiovascular risk reduction similar to that demonstrated with existing GLP-1 receptor agonists and dual agonists.

Finally, the cohosts reflects on the growing enthusiasm among patients, many of whom are already aware of the topline data through widespread media coverage. The speakers note increasing patient interest in pharmacologic alternatives to bariatric surgery, particularly among individuals seeking less invasive treatment options or those unable to accommodate surgical recovery. They conclude that retatrutide and other emerging triple agonists may represent the beginning of a new era in obesity medicine and chronic weight management, with anticipation building ahead of the full data presentation and potential publication expected at the upcoming ADA Scientific Sessions.

Editor’s Note: Isaacs reports disclosures with Dexcom, Abbott, Lilly, Novo Nordisk, Medtronic, Insulet, and others. Bellini reports disclosures with Abbott Diabetes Care, MannKind, Povention Bio, and others.

References

1. Eli Lilly. Lilly’s triple agonist, retatrutide, delivered powerful weight loss in pivotal Phase 3 obesity trial. May 21, 2026. Accessed May 29, 2026. https://investor.lilly.com/news-releases/news-release-details/lillys-triple-agonist-retatrutide-delivered-powerful-weight-loss