Retatrutide Phase 3 Results: What Canadians Should Know About TRIUMPH-2

Updated October 1, 2026. Retatrutide is drawing renewed attention after Eli Lilly released detailed Phase 3 TRIUMPH-2 results in adults living with obesity or overweight and type 2 diabetes. The investigational medicine targets three hormone receptors—GIP, GLP-1 and glucagon—and remains under clinical development.

Important Canadian context: Retatrutide is not authorized by Health Canada. Health Canada has warned consumers about unauthorized injectable peptide products sold online and states that unauthorized drug products have not been assessed for safety, efficacy or quality. This article is for educational purposes and does not constitute medical advice or a recommendation to use an investigational product.

What did the new TRIUMPH-2 Phase 3 study find?

In Lilly’s detailed September 29, 2026 report from TRIUMPH-2, adults with obesity or overweight and type 2 diabetes who received retatrutide 12 mg lost an average of 49.6 lb (22.5 kg), or 20.8% of body weight, over 80 weeks using the efficacy estimand. Participants with a starting BMI of 35 or higher lost up to an average of 23.4% of body weight at the same dose.

Lilly also reported an average A1C reduction of up to 1.6 percentage points, while up to 40% of participants reached an A1C below 5.7%. More than half of participants taking 12 mg no longer met BMI criteria for obesity at the end of the trial.

These findings were presented at the 2026 Annual Meeting of the European Association for the Study of Diabetes (EASD). The study was sponsored by Eli Lilly, the developer of retatrutide.

What is retatrutide?

Retatrutide is an investigational once-weekly peptide-based medicine designed to activate three metabolic hormone receptors: glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1) and glucagon. This is why it is often described as a “triple agonist.”

The scientific idea is to influence several pathways involved in appetite, glucose regulation and energy metabolism at the same time. That mechanism distinguishes retatrutide from semaglutide, which targets the GLP-1 receptor, and tirzepatide, which targets GIP and GLP-1 receptors.

Why are the TRIUMPH-2 results important?

People living with type 2 diabetes have often experienced less weight reduction in obesity-drug trials than participants without diabetes. TRIUMPH-2 therefore provides important Phase 3 evidence in a population where both weight and glycemic control matter.

The result also expands the discussion beyond weight alone. A1C, waist circumference, blood pressure, lipids and other cardiometabolic markers are increasingly important when evaluating obesity treatments. Long-term cardiovascular and kidney outcome studies remain necessary to determine whether improvements in intermediate markers translate into fewer major clinical events.

How does retatrutide compare with tirzepatide and semaglutide?

Direct comparisons should be made cautiously. Different trials enroll different populations, use different treatment durations, titration schedules, statistical estimands and background therapies. A higher percentage reported in one trial does not automatically mean one medicine is superior to another in clinical practice.

Mechanistically, the main distinction is receptor targeting: semaglutide is a GLP-1 receptor agonist, tirzepatide activates GIP and GLP-1 receptors, and retatrutide activates GIP, GLP-1 and glucagon receptors. Head-to-head Phase 3 research will be more informative than cross-trial comparisons.

What are the main limitations and side effects?

Retatrutide remains investigational, which means the complete benefit-risk profile is still being established. Gastrointestinal adverse events such as nausea, diarrhea, vomiting and constipation have been among the most commonly reported side effects in studies of retatrutide and other incretin-based therapies. Trial discontinuation, dose escalation and the difference between efficacy and treatment-regimen estimands should also be considered when interpreting headline weight-loss figures.

TRIUMPH-2 was sponsored by Eli Lilly. Independent replication, regulatory review, longer-term safety monitoring and completed outcomes studies will all contribute to understanding how the medicine may eventually fit into clinical care.

Is retatrutide approved in Canada?

No. As of October 1, 2026, retatrutide is not authorized by Health Canada. Health Canada has specifically warned Canadians about unauthorized injectable peptides, including retatrutide, sold online. Products that have not been authorized have not undergone Health Canada’s assessment for safety, efficacy and quality.

Canadians considering treatment for obesity or type 2 diabetes should discuss authorized treatment options with a licensed healthcare professional and obtain prescription medicines through licensed pharmacies.

When could retatrutide become available?

Lilly has continued its Phase 3 development program and has indicated plans for regulatory submissions after completion of the necessary studies. Regulatory timelines can change, and approval is never guaranteed. Health Canada would independently review any future Canadian submission before the medicine could be authorized for sale in Canada.

What should Canadians watch next?

The most important next steps include additional Phase 3 results, head-to-head comparisons, longer-term safety data, cardiovascular and kidney outcomes, and future regulatory submissions. Researchers will also continue examining whether targeting GIP, GLP-1 and glucagon together provides clinically meaningful advantages beyond weight reduction alone.

Frequently asked questions

Is retatrutide the same as Ozempic?

No. Ozempic contains semaglutide and acts primarily through the GLP-1 receptor. Retatrutide is an investigational triple agonist targeting GIP, GLP-1 and glucagon receptors.

Is retatrutide the same as tirzepatide?

No. Tirzepatide is a dual GIP/GLP-1 receptor agonist. Retatrutide adds glucagon-receptor activity and is still investigational.

How much weight was lost in TRIUMPH-2?

Lilly reported average weight loss of up to 20.8% over 80 weeks in participants receiving 12 mg under the efficacy estimand. Outcomes differed by dose and statistical estimand.

Can Canadians legally buy retatrutide for medical use?

Retatrutide is not authorized by Health Canada. Health Canada warns against unauthorized injectable peptide products sold online and recommends using prescription medicines only under the care of a licensed healthcare professional and through licensed pharmacies.

Sources

Eli Lilly and Company: TRIUMPH-2 Phase 3 detailed results, September 29, 2026.

Health Canada: Think twice before injecting peptides bought online.

The Lancet: Phase 3 retatrutide evidence in type 2 diabetes (TRANSCEND-T2D-1).