TRIUMPH-2: Retatrutide at 80 Weeks

TRIUMPH-2 was a randomized phase 3 trial in 1,152 adults with obesity and type 2 diabetes. At week 80, mean bodyweight changed by -11.9% with retatrutide 4 mg, -16.8% with 9 mg, and -18.8% with 12 mg, compared with -5.1% on placebo. The differences versus placebo were statistically significant for all three dose groups^[1]. Gastrointestinal events were more frequent with retatrutide, and the higher-dose groups had more permanent discontinuations due to adverse events or death than placebo. This is a strong efficacy result, but it comes from one company-funded trial in a defined population. Retatrutide remains investigational.

Who took part

The trial enrolled adults aged 18 or older at 92 medical and research sites across eight countries. Eligibility required a body mass index of at least 27 kg/m², type 2 diabetes with HbA1c from 6.5% to 10.5%, stable diabetes treatment, and at least one previous unsuccessful dietary effort to reduce weight. Participants could be managing diabetes with diet and exercise alone or with up to three oral glucose-lowering medicines^[1]. The trial registry also excluded people with type 1 diabetes, recent use of weight-loss drugs, previous or planned obesity surgery, a history of pancreatitis, or certain thyroid-cancer risks^[2].

The mean age was 55.1 years and mean baseline BMI was 38.2 kg/m². Women made up 48% of the randomized group, and 58% of participants were recorded as White. Median obesity duration was 21 years, while median diabetes duration was 5.6 years. Most participants, 92%, were using at least one oral glucose-lowering medicine at baseline. Those details matter because they set the limits of the result. This was not a trial in people without diabetes, adolescents, or people starting with a BMI below 27 kg/m².

How TRIUMPH-2 was run

Participants were assigned in equal proportions to weekly subcutaneous placebo or retatrutide at 4 mg, 9 mg, or 12 mg. The study was double-blind and parallel-group. Its primary endpoint was percentage change in bodyweight from baseline to week 80 for the 9 mg and 12 mg groups versus placebo, with the 4 mg comparison listed as a key secondary endpoint. The registry records the trial as completed and identifies Eli Lilly and Company as the sponsor^[2]. The Lancet paper also lists Lilly as the funder^[1].

The published percentages use the treatment-regimen estimand. That analysis included all randomized participants and used multiple imputation for missing data. In plain language, the estimate was designed to reflect outcomes under the assigned treatment policy rather than report only the people who stayed on treatment through week 80. Of the 1,152 randomized participants, 965, or 84%, completed the study drug. Completion is relevant when reading a long-duration mean because missing outcomes require statistical handling.

Weight loss and glycaemic findings

At 80 weeks, estimated differences in bodyweight change versus placebo were -6.9 percentage points for 4 mg, -11.8 points for 9 mg, and -13.8 points for 12 mg. The 95% confidence intervals did not cross zero, and each comparison had a reported p value below 0.0001^[1]. The dose groups therefore separated clearly from placebo on the prespecified weight endpoint. The paper's abstract also reports improved glycaemic control, but it does not provide the exact HbA1c changes. We are not supplying numbers that the accessible record does not state.

These results apply to retatrutide as tested in this protocol. They should not be treated as a direct comparison with semaglutide, tirzepatide, or another obesity medicine because TRIUMPH-2 did not randomize participants against those drugs. For background on the molecule, see the retatrutide research summary. The retatrutide overview also separates published trial evidence from the status of products marketed outside authorized channels.

Adverse events and discontinuations

Diarrhoea was reported in 27% of the 4 mg group and 34% of both higher-dose groups, compared with 13% on placebo. Nausea affected 14%, 21%, and 28% across the ascending retatrutide groups, compared with 8% on placebo. Hypotension was reported in 1%, 5%, and 6%, respectively, versus less than 1% with placebo. Dysesthesia, an abnormal-sensation category, was reported in 4%, 6%, and 7%, versus 1% on placebo^[1]. These are event frequencies within the trial, not forecasts for an individual patient.

Permanent treatment discontinuation due to adverse events or death occurred in 4% of the 4 mg group, 12% of the 9 mg group, 8% of the 12 mg group, and 5% of the placebo group. Seven participants died: two in the 4 mg group, three in the 9 mg group, one in the 12 mg group, and one on placebo. Investigators judged all deaths unrelated to the study intervention^[1]. That judgment is important context, but the study still needs full scrutiny of adverse-event timing and causes. The abstract alone does not provide those case-level details.

What we don't yet know

TRIUMPH-2 answers a specific 80-week question. It does not establish durability after treatment stops, rare risks that require a much larger population, or outcomes beyond the follow-up reported here. It also cannot show whether retatrutide is better than an active comparator. The registered secondary outcomes include blood pressure, waist circumference, lipids, HbA1c, fasting glucose, and physical functioning, but the accessible PubMed abstract does not report their numerical results^[2]. Those data need the full paper or later analyses before they can be described precisely.

Retatrutide was still under investigation when this paper was published. A trial result is not a regulatory approval, a prescribing recommendation, or evidence that an unapproved product sold online matches the study medicine. Readers can find the wider evidence and safety context in the retatrutide safety section. Anyone considering an obesity or diabetes treatment should discuss authorized options, expected benefits, and individual risks with a qualified healthcare professional.

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