Retatrutide Beats Ozempic in Phase III Trial, Delivering More Than Twice the Weight Loss

MEDISEARCHER NEWS

Global · Diabetes & weight management · 29 October 2026

Experimental weight-loss and diabetes drug retatrutide produced more than twice the average percentage weight loss of the highest approved dose of Ozempic in a major head-to-head Phase III trial, while also delivering a greater reduction in blood sugar.

The TRANSCEND-T2D-2 trial directly compared once-weekly retatrutide with Ozempic 2 mg in 1,298 adults with type 2 diabetes.

After 80 weeks, people receiving the highest retatrutide dose had lost an average of 20.9% of their body weight, compared with 9.4% among participants receiving Ozempic.

The results provide the strongest direct evidence so far of how Lilly’s experimental triple-hormone drug could compare with an established GLP-1 medicine if retatrutide ultimately receives regulatory approval.

How did retatrutide compare with Ozempic?

TRANSCEND-T2D-2 compared two target doses of retatrutide — 9 mg and 12 mg — with the 2 mg dose of Ozempic (semaglutide).

At the start of the trial, participants had an average body weight of 102.4 kg (225.8 lb) and an average body mass index of 36.8 kg/m².

At 80 weeks, average weight loss was:

• 19.5%, or 20.1 kg (44.3 lb), with retatrutide 9 mg;
• 20.9%, or 21.5 kg (47.4 lb), with retatrutide 12 mg; and
• 9.4%, or 9.5 kg (20.9 lb), with Ozempic 2 mg.

Both retatrutide doses therefore produced more than twice the average percentage weight loss seen with Ozempic in the trial.

The weight-loss comparisons were statistically significant, with p-values below 0.001.

Retatrutide also reduced HbA1c more than Ozempic

The trial primarily evaluated blood-sugar control because the participants had type 2 diabetes.

Average HbA1c at baseline was 8.3%.

After 80 weeks, HbA1c had fallen by:

• 2.2 percentage points with retatrutide 9 mg;
• 2.2 percentage points with retatrutide 12 mg; and
• 1.8 percentage points with Ozempic 2 mg.

The trial’s primary objective was to demonstrate that retatrutide 12 mg was at least noninferior to Ozempic 2 mg for HbA1c reduction.

Retatrutide 12 mg went further and demonstrated statistically significant superiority over Ozempic for HbA1c reduction.

The 9 mg dose met the prespecified noninferiority endpoint and showed nominal statistical superiority for HbA1c reduction.

What is retatrutide?

Retatrutide is an experimental once-weekly injectable medicine being developed by Eli Lilly for obesity, type 2 diabetes and several related metabolic conditions.

It belongs to the rapidly expanding family of medicines that influence hormone pathways involved in appetite, blood-sugar regulation and metabolism.

But retatrutide differs from existing GLP-1 medicines because one molecule activates three hormone receptors:

• glucose-dependent insulinotropic polypeptide (GIP);
• glucagon-like peptide-1 (GLP-1); and
• glucagon.

Ozempic activates the GLP-1 receptor, while Lilly’s tirzepatide — sold as Mounjaro for type 2 diabetes and under obesity indications in different markets — activates both GIP and GLP-1 receptors.

Retatrutide adds glucagon-receptor activity to those two pathways, making it a so-called triple receptor agonist.

Why is the head-to-head comparison important?

Weight-loss medicines are often compared using results from separate clinical trials, but those comparisons have important limitations.

Different trials can involve different patient populations, treatment durations, dosing schedules and statistical methods.

TRANSCEND-T2D-2 is different because participants were randomized within the same Phase III trial to receive either retatrutide or Ozempic.

It therefore provides much stronger comparative evidence than simply placing results from unrelated retatrutide and semaglutide studies next to each other.

The comparison is also clinically relevant because the trial used Ozempic 2 mg, the highest approved Ozempic dose.

Does this mean retatrutide is twice as effective as Ozempic?

Not exactly.

The trial found that average percentage weight loss with retatrutide was more than twice that observed with Ozempic 2 mg: up to 20.9% versus 9.4% at 80 weeks.

That does not mean retatrutide is universally “twice as effective” for every clinical outcome or that every patient taking retatrutide will lose twice as much weight.

Individual responses to incretin medicines vary substantially, and treatment effectiveness also includes blood-sugar control, cardiovascular outcomes, tolerability, safety and the ability to remain on treatment.

The current results apply specifically to the population and endpoints studied in TRANSCEND-T2D-2.

Who participated in TRANSCEND-T2D-2?

The randomized, open-label Phase III trial enrolled 1,298 adults whose type 2 diabetes was inadequately controlled with metformin, with or without an SGLT2 inhibitor.

Participants entered the study with HbA1c levels between 7.0% and 10.5%.

They were randomized in a 2:2:1 ratio to receive:

• retatrutide 9 mg once weekly;
• retatrutide 12 mg once weekly; or
• Ozempic 2 mg once weekly.

Retatrutide treatment began at 2 mg and was increased every four weeks until participants reached their assigned target dose.

The study also includes an extension period in which approximately 650 participants continue retatrutide for another 24 weeks to provide additional information about longer-term efficacy and safety.

What side effects occurred with retatrutide?

As with existing incretin medicines, gastrointestinal side effects were among the most common adverse events.

Reported rates for retatrutide 9 mg, retatrutide 12 mg and Ozempic 2 mg respectively included:

• diarrhea: 28.3%, 32.7% and 26.4%;
• nausea: 21.2%, 23.8% and 21.3%;
• constipation: 14.2%, 13.1% and 19.8%;
• vomiting: 10.2%, 15.0% and 13.2%; and
• dyspepsia: 10.4%, 8.5% and 11.6%.

Lilly said most of these events were mild to moderate and typically resolved during treatment.

More patients stopped retatrutide because of side effects

One important difference was the proportion of participants who discontinued treatment because of adverse events.

Discontinuation rates were:

• 4.8% with retatrutide 9 mg;
• 7.9% with retatrutide 12 mg; and
• 2.7% with Ozempic 2 mg.

This means the higher efficacy seen with retatrutide — particularly at 12 mg — needs to be considered alongside its tolerability.

What is dysesthesia and why was it reported?

The trial also reported dysesthesia, a term describing abnormal sensations such as tingling, burning, altered skin sensation or heightened sensitivity.

Dysesthesia occurred in:

• 4.8% of participants receiving retatrutide 9 mg;
• 6.5% receiving retatrutide 12 mg; and
• 2.7% receiving Ozempic.

The finding will be worth following as more detailed safety data from the Phase III programme become available.

Is retatrutide approved?

No. Retatrutide remains an investigational medicine.

It has not been approved by the US Food and Drug Administration, European Medicines Agency, UK Medicines and Healthcare products Regulatory Agency, Australian Therapeutic Goods Administration or any other medicines regulator.

It therefore cannot currently be prescribed as an approved medicine.

The new Phase III results do not themselves constitute regulatory approval.

Can you buy retatrutide online?

There is currently no legitimate approved retatrutide product available for patients to buy.

This distinction is particularly important because websites, social-media sellers, clinics and other vendors have advertised products claiming to contain retatrutide while the medicine is still undergoing clinical trials.

Lilly states that retatrutide has not been approved by any regulatory authority anywhere in the world and cannot legally be sold or marketed for human use.

Products advertised online as “retatrutide”, “research retatrutide” or similar formulations are not equivalent to obtaining an approved prescription medicine through a regulated pharmacy.

Illicit products may contain incorrect quantities of active ingredients, contaminants or entirely different substances.

Are these results peer reviewed?

Not yet.

The TRANSCEND-T2D-2 findings announced on 28 October 2026 are topline Phase III results released by Eli Lilly.

The trial itself is a large randomized Phase III study, which makes the evidence substantially more mature than early-stage or small exploratory research.

However, the full dataset has not yet been published in a peer-reviewed medical journal.

Lilly says detailed TRANSCEND-T2D-2 results will be presented at a future medical meeting and submitted for publication in a peer-reviewed journal.

That distinction is important when interpreting the results. The headline efficacy numbers are from a completed late-stage trial, but independent assessment of the complete dataset will become possible only after detailed results are released.

When could retatrutide become available?

There is currently no approved retail launch date for retatrutide.

Lilly is running an extensive Phase III development programme examining the medicine across type 2 diabetes, obesity and overweight, cardiovascular outcomes and several obesity-related conditions.

Regulatory authorities would need to review a formal marketing application and determine whether the evidence supports approval before retatrutide could become a routinely prescribed medicine.

Even after regulatory approval, actual availability, pricing, insurance coverage and reimbursement could differ substantially between the United States, United Kingdom, European Union, Australia and other markets.

What happens next?

The next major step will be publication and presentation of the detailed TRANSCEND-T2D-2 results.

Further evidence will also come from other trials in the retatrutide Phase III programme.

One particularly important study is TRIUMPH-5, which is directly comparing retatrutide with tirzepatide in adults with obesity, with or without type 2 diabetes.

That comparison could help establish whether adding glucagon-receptor activity provides a meaningful advantage over the dual GIP/GLP-1 mechanism already used by tirzepatide.

Regulatory submissions will then determine whether the efficacy demonstrated across the programme is accompanied by a safety and benefit-risk profile sufficient for approval.

Why these results matter

The rapid development of GLP-1 and related medicines has already changed the treatment of type 2 diabetes and obesity.

TRANSCEND-T2D-2 suggests that the next generation of incretin-based medicines could potentially push weight loss substantially further even among people with type 2 diabetes, a population in which achieving very large reductions in body weight has historically been difficult.

But the trial also illustrates why headline weight-loss percentages are only part of the story.

Retatrutide remains experimental, detailed results have not yet undergone peer review, and adverse-event discontinuation was higher than with Ozempic — particularly at the 12 mg dose that produced the greatest weight loss.

For now, the result is best understood as strong late-stage evidence for a potentially important future treatment, rather than evidence that patients can or should switch from an approved medicine to retatrutide today.

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Sources and verification

MediSearcher reviewed the following primary and authoritative sources when preparing this article:

• Eli Lilly: TRANSCEND-T2D-2 Phase III topline results — retatrutide compared with Ozempic 2 mg
• ClinicalTrials.gov: TRANSCEND-T2D-2 Phase III trial (NCT06260722)
• Eli Lilly: Retatrutide investigational status and patient safety information

This article is for general informational purposes only and is not medical advice. Retatrutide is an investigational medicine and is not approved for human use. Patients should not use products sold online or elsewhere as retatrutide outside an appropriately authorised clinical trial. People using Ozempic, Mounjaro or other prescription medicines should discuss treatment decisions with an appropriately qualified healthcare professional.