The biggest retatrutide news of the week is being presented this morning in Milan. At the 62nd Annual Meeting of the European Association for the Study of Diabetes (EASD), running 28 September to 2 October 2026, Eli Lilly is running a dedicated symposium on the full Phase 3 retatrutide results from TRIUMPH-2 — the trial in adults who have both obesity or overweight and type 2 diabetes. That is the hardest population in obesity medicine to move, and it is also the one where the headline percentage you read depends heavily on which number a journalist picked up.

Here is what was actually reported, and why two different figures are circulating from the same trial.

Retatrutide results in type 2 diabetes: what TRIUMPH-2 showed

TRIUMPH-2 randomised 1,152 adults with type 2 diabetes and obesity or overweight to retatrutide 4mg, 9mg or 12mg, or placebo, for 80 weeks. Baseline body weight averaged 106.4kg and baseline A1c averaged 7.7%.

Per Lilly's results announcement:

  • 4mg: average 12.7% body weight loss (about 13.5kg)
  • 9mg: average 19.1% (about 20.6kg)
  • 12mg: average 20.8% (about 22.5kg)
  • A1c: reductions of up to 1.6 percentage points, versus 0.2 points on placebo

And the figure Lilly is leading with at EASD: roughly 60% of participants dropped below the obesity threshold of BMI 30. In a cohort defined by having type 2 diabetes on top of obesity, that is a striking categorical shift rather than a marginal one.

For background on how the three-receptor mechanism differs from single- and dual-agonists, see what is retatrutide.

The diabetes gap is real — and retatrutide didn't erase it

Across the incretin class, people with type 2 diabetes consistently lose less weight than people with obesity alone on the same drug. Retatrutide is no exception. Compare the 12mg arms across the TRIUMPH programme:

Trial Population 12mg weight loss
TRIUMPH-1 Obesity, no diabetes 28.3% at 80 weeks
TRIUMPH-2 Obesity/overweight + type 2 diabetes 20.8% at 80 weeks
TRIUMPH-3 Severe obesity + established CVD up to 22.6% at 80 weeks

Same molecule, same top dose, same 80-week window — roughly 7.5 percentage points less weight loss when diabetes is in the room. Nobody should read the 28.3% TRIUMPH-1 number and assume it transfers to a person with type 2 diabetes. More on the trial programme at clinical trials.

Why you'll see 20.8% in one place and 18.8% in another

Coverage of the EASD presentation from Endpoints News cited weight loss of "up to 18.8%" — lower than the 20.8% in Lilly's own results announcement. That is not a contradiction; it is almost certainly a difference in estimand, the statistical rule for how a trial handles people who stop the drug or add another weight-loss treatment.

Obesity trials routinely report two:

  • the efficacy estimand, which estimates the effect if participants stayed on treatment;
  • the treatment-regimen estimand, which counts everyone regardless of adherence and is therefore more conservative.

In TRIUMPH-1, the same trial produced 19.0% / 25.9% / 28.3% on the efficacy estimand and 17.6% / 23.7% / 25.0% on the treatment-regimen estimand. A gap of two to three percentage points between the two is normal. We have not seen Lilly publish a labelled treatment-regimen figure for TRIUMPH-2, so we're flagging the discrepancy rather than declaring which number is "the" number — that will be settled by the peer-reviewed publication, not a conference slide or a press release.

The practical point for readers: whenever you see a weight-loss percentage quoted for any of these drugs, the useful question is which estimand, at what week, in which population. Three different honest answers can come out of one trial.

Tolerability

Side effects in TRIUMPH-2 and TRIUMPH-3 were predominantly gastrointestinal — nausea, diarrhoea, vomiting — mostly mild to moderate and concentrated during dose escalation. Discontinuation due to adverse events ran from roughly 3.8% to 11.6% across retatrutide doses versus 4.9% on placebo, rising with dose. Lilly also noted that major adverse cardiovascular events in TRIUMPH-3 occurred less frequently than anticipated in both the retatrutide and placebo arms, which limits what can be concluded about cardiovascular risk reduction from that trial. See safety for the fuller picture.

What this means from Australia

Retatrutide is investigational everywhere — it is not approved by the FDA, the EMA or the TGA. Lilly has said it plans to file a Biologics License Application with the FDA in the first quarter of 2027, and an Australian submission has not been announced. With roughly 66.8% of Australian adults living with overweight or obesity, and type 2 diabetes frequently travelling alongside it, TRIUMPH-2 is the trial that most closely matches a very large slice of the Australian population — which is exactly why the estimand question matters here rather than being a statistical footnote. Our Australia page tracks regulatory status as it changes.

Join the free updates list and we'll email you when TRIUMPH-2 is published in full, and when any TGA filing is confirmed.

FAQ

What were the retatrutide results in people with type 2 diabetes?

In the Phase 3 TRIUMPH-2 trial, adults with type 2 diabetes and obesity or overweight lost an average of 12.7%, 19.1% and 20.8% of body weight on retatrutide 4mg, 9mg and 12mg respectively over 80 weeks, with A1c reductions of up to 1.6 percentage points. Around 60% fell below the BMI 30 obesity threshold.

Why is retatrutide weight loss lower in people with diabetes?

People with type 2 diabetes consistently lose less weight than people with obesity alone on incretin-based drugs, and retatrutide follows that pattern: 20.8% at 12mg in TRIUMPH-2 versus 28.3% at 12mg in TRIUMPH-1, which excluded diabetes. The trials do not establish the mechanism behind the gap.

Why do different sources quote different retatrutide weight-loss numbers?

Because obesity trials report more than one estimand. The efficacy estimand estimates the effect for people who stay on treatment; the treatment-regimen estimand counts everyone regardless of adherence and is lower. In TRIUMPH-1 the two differed by 2–3 percentage points at each dose.

Is retatrutide approved anywhere yet?

No. Retatrutide remains investigational worldwide and is not approved by the TGA, FDA or EMA. Eli Lilly has stated it plans to submit a Biologics License Application to the FDA in Q1 2027; approval and timing are not guaranteed.

Sources

This article is independent information only and is not medical advice. retatrutide.net.au is not affiliated with, endorsed by or sponsored by Eli Lilly and Company. Retatrutide is investigational and is not approved by the TGA, FDA or EMA. Speak with a qualified Australian health professional about any weight-management or diabetes treatment decision.