The main finding
In one sentence: In an 80-week phase 3 trial of 1152 adults with obesity and type 2 diabetes, average weight change was -11.9%, -16.8% and -18.8% with weekly retatrutide at 4, 9 and 12 mg, compared with -5.1% with placebo.
Group averages, not an individual prediction. A trial result describes what happened to a defined group over a defined time.
On this page
Why this study matters
Retatrutide is an experimental medicine. As of October 2026, it is not approved in Canada or in any other country, and this study is research only. It acts on three hormone receptors: GIP, GLP-1 and glucagon. TRIUMPH-2 is a large, late-stage (phase 3) trial of retatrutide in adults who have both obesity and type 2 diabetes. A separate trial, TRIUMPH-1, studied people without diabetes.
Who was in the study
The trial randomized 1152 adults at 92 centres in eight countries. Everyone was 18 or older, had type 2 diabetes and a BMI of 27 or higher. BMI, or body mass index, is weight in kilograms divided by height in metres squared. Their HbA1c was between 6.5% and 10.5%. HbA1c is a blood test that reflects average blood sugar over the past few months. Each person had been on stable diabetes treatment for at least 90 days, either diet and exercise alone or up to three diabetes pills, and had tried at least once to lose weight by changing their diet.
At the start, the average age was 55.1 years. In all, 554 people (48%) were female and 598 (52%) were male, and 672 (58%) were of White ethnicity. The average BMI was 38.2 and the average HbA1c was 7.71%. The median, or middle value, for time living with obesity was 21 years, and for time living with diabetes it was 5.6 years. Of the 1152 people, 1055 (92%) were taking at least one diabetes pill. The published summary we reviewed does not name the countries.
What the researchers did
This was a phase 3, randomized, double-blind, placebo-controlled trial. Randomized means an online system assigned people to a group by chance, in equal numbers. Double-blind means neither participants nor staff knew who was getting retatrutide and who was getting placebo, an injection with no medicine in it.
People injected themselves once a week with retatrutide 4 mg, 9 mg or 12 mg, or placebo. The main result was the percentage change in body weight from the start to week 80, comparing the 9 mg and 12 mg groups with placebo. The 4 mg comparison was a key secondary result.
The analysis used a treatment-regimen estimand. An estimand is the exact question the statistics answer. This one includes everyone who was randomized, whether or not they kept taking the injections. Missing data were filled in with a statistical method called multiple imputation.
What they found
At week 80, average weight change was -11.9% with 4 mg, -16.8% with 9 mg and -18.8% with 12 mg, compared with -5.1% with placebo (R33-C04). The table shows the difference between each dose and placebo. A confidence interval, or CI, is the range of values the data are reasonably consistent with.
| Group | Weight change at 80 weeks | Difference from placebo (95% CI) |
|---|---|---|
| Retatrutide 4 mg | -11.9% | -6.9% (-8.7 to -5.1) |
| Retatrutide 9 mg | -16.8% | -11.8% (-13.7 to -9.8) |
| Retatrutide 12 mg | -18.8% | -13.8% (-15.8 to -11.8) |
| Placebo | -5.1% | Comparison group |
All three differences had P below 0.0001. The authors report that blood sugar control also improved with retatrutide, but the published summary we reviewed does not give HbA1c numbers.
Side effects and people who stopped
Stomach and bowel side effects were the most common, and were more frequent with retatrutide than with placebo. Low blood pressure (hypotension) and dysesthesia were also more frequent with retatrutide (R33-C06). Dysesthesia means an unusual or unpleasant skin sensation.
| Side effect | 4 mg | 9 mg | 12 mg | Placebo |
|---|---|---|---|---|
| Diarrhea | 27% | 34% | 34% | 13% |
| Nausea | 14% | 21% | 28% | 8% |
| Low blood pressure | 1% | 5% | 6% | under 1% |
| Dysesthesia | 4% | 6% | 7% | 1% |
Stopping treatment for good because of side effects or death happened in 4% of the 4 mg group, 12% of the 9 mg group and 8% of the 12 mg group, compared with 5% with placebo (R33-C05). Overall, 965 of 1152 people (84%) completed the study treatment.
Deaths during the trial were two in the 4 mg group, three in the 9 mg group, one in the 12 mg group and one in the placebo group. The investigators judged that none of the deaths were related to the study treatment.
What this study does not tell you
- Our summary is based on the abstract only. It does not give HbA1c results, low blood sugar rates or how long side effects lasted.
- The summary does not describe the dysesthesia finding in detail, such as whether it went away.
- The trial ran for 80 weeks. It does not show what happens over longer periods or after stopping.
- Company news releases and media stories may report a different estimand, such as results only in people who kept taking the medicine, which can give different numbers.
- Do not compare these percentages with trials in people without diabetes, or with trials of other medicines.
- The trial was funded by Eli Lilly and Company, which is developing retatrutide, and several authors work for the company.
What it means in Canada
As of October 2026, retatrutide is not approved in Canada or in any other country. On 9 April 2026, Health Canada warned about unauthorized peptides sold online, including retatrutide. This trial does not change that status. You can follow emerging medicines on our medicines page. For medicines available in Canada, see semaglutide in Canada, tirzepatide in Canada and public drug coverage by province.
Common questions
How much weight did people with type 2 diabetes lose on retatrutide in TRIUMPH-2?
Over 80 weeks, average weight change was -11.9% at 4 mg, -16.8% at 9 mg and -18.8% at 12 mg, compared with -5.1% with placebo.
What side effects were reported with retatrutide in TRIUMPH-2?
Diarrhea and nausea were the most common. Low blood pressure and dysesthesia, an unusual skin sensation, were also more frequent than with placebo, for example 6% and 7% at 12 mg versus under 1% and 1% with placebo.
Is retatrutide approved in Canada?
No. As of October 2026, retatrutide is not approved in Canada or anywhere else. TRIUMPH-2 is a research trial of an investigational medicine.
Related reading
Other studies in this library that bear on the same question.
TRIUMPH-1: retatrutide for weight loss over 80 weeks
Retatrutide in type 2 diabetes: a 36-week phase 2 trial
TRANSCEND-T2D-1: retatrutide alone in early type 2 diabetes
Retatrutide and body fat: a DXA substudy in type 2 diabetes
Tirzepatide for weight loss in type 2 diabetes: SURMOUNT-2
Source
Original paper: Virginia Bellido, Emerging evidence: TRIUMPH-2, Lancet (London, England), 2026. PubMed: https://pubmed.ncbi.nlm.nih.gov/42810372/. DOI: https://doi.org/10.1016/S0140-6736(26)01861-1. Funding: The trial was funded by Eli Lilly and Company, the company developing retatrutide. How we summarized it: abstract and extracted data.
This page explains a published study. It is not medical advice and does not describe whether a medicine is right for you. Talk to your doctor, nurse practitioner or pharmacist about your own situation. Reviewed and signed by two pharmacists registered in British Columbia, 2026-10-04.
Evidence records behind this page
Each record is a row in the clinical evidence file, taken from the published paper named above. The caution column is the limit the researcher recorded for that number.
This table scrolls sideways.
| Record | What the paper reports | Type | Population | Caution | Source |
|---|---|---|---|---|---|
| R33-C04 | In TRIUMPH-2 (1152 adults with obesity and type 2 diabetes), mean 80-week body-weight change was -11.9%, -16.8% and -18.8% with retatrutide 4, 9 and 12 mg versus -5.1% with placebo; estimated treatment differences were -6.9% (95% CI -8.7 to -5.1), -11.8% (-13.7 to -9.8) and -13.8% (-15.8 to -11.8). | direct evidence | Adults with T2D (HbA1c 6.5 to 10.5%) and BMI at least 27, on diet/exercise or up to three oral glucose-lowering medicines | Treatment-regimen estimand with multiple imputation. HbA1c results not given numerically in abstract. Manufacturer-funded. Abstract-only. As of October 2026 retatrutide is not approved anywhere; Health Canada warned on 2026-04-09 about unauthorized peptides sold online including retatrutide. | PubMed 42810372 |
| R33-C05 | In TRIUMPH-2, permanent treatment discontinuation due to adverse events or death occurred in 4% (4 mg), 12% (9 mg) and 8% (12 mg) of retatrutide groups versus 5% with placebo. | direct evidence | Adults with T2D (HbA1c 6.5 to 10.5%) and BMI at least 27 | Outcome combines adverse events and death. Rates are not dose-ordered (9 mg higher than 12 mg). 965 of 1152 (84%) completed study drug. Abstract-only. As of October 2026 retatrutide is not approved anywhere; Health Canada warned on 2026-04-09 about unauthorized peptides sold online including retatrutide. | PubMed 42810372 |
| R33-C06 | In TRIUMPH-2, hypotension occurred in 1%, 5% and 6% of retatrutide 4, 9 and 12 mg groups versus under 1% with placebo, and dysesthesia in 4%, 6% and 7% versus 1%; diarrhoea (27%, 34%, 34% vs 13%) and nausea (14%, 21%, 28% vs 8%) were the most frequent adverse events. | direct evidence | Adults with T2D (HbA1c 6.5 to 10.5%) and BMI at least 27 | Dysesthesia characteristics, duration and resolution not described in abstract. Safety denominators differ slightly from randomized numbers. Abstract-only. As of October 2026 retatrutide is not approved anywhere; Health Canada warned on 2026-04-09 about unauthorized peptides sold online including retatrutide. | PubMed 42810372 |