Eli Lilly has released the full results of a large, late-stage study of retatrutide, an experimental weekly injection for weight loss. The findings were presented at a major European diabetes conference in Milan and published in The Lancet. They build on early headline numbers the company shared in July.
What is retatrutide?
Most people know drugs like Ozempic, Wegovy, Mounjaro and Zepbound. These drugs work by copying one or two natural gut hormones that help control appetite and blood sugar. Retatrutide goes a step further. It acts on three hormone pathways (GLP-1, GIP and glucagon), which is why it’s sometimes called a “triple-G” drug. The idea is that hitting all three may lead to more weight loss than today’s Health Canada approved options.
Who was in the study?
The trial, called TRIUMPH-2, followed 1,152 adults who had both obesity and type 2 diabetes. Participants got one of three doses of retatrutide or a placebo (an inactive shot) for 80 weeks, about a year and a half.
How much weight did people lose?
On the highest dose (12 mg), people lost about 21% of their body weight on average. The placebo group lost about 4%. The more detailed results show:
- Roughly 1 in 3 people on the top dose lost a quarter or more of their body weight.
- About half lost at least 20%.
- More than half dropped below the body mass index (BMI) cutoff for obesity.
For comparison, in an earlier trial of tirzepatide (Mounjaro/Zepbound), about a third of people lost 20% or more. That’s a meaningful gap, though the two studies weren’t identical, so the comparison is only a rough one.
What about blood sugar?
Blood sugar is where the picture gets more mixed. People started the study with an average A1C (a measure of blood sugar over about three months) of 7.7%. It dropped by about 1.4 to 1.6 points on retatrutide, compared with almost no change on placebo. Higher doses didn’t lower A1C any further. About 4 in 10 people on the middle and top doses reached a normal, non-diabetic A1C. That’s lower than the up to 55% seen with tirzepatide in a separate trial. In short, retatrutide seems to be stronger for weight loss but not better for blood sugar.
Heart health signs
On the top dose, the study also found improvements in several heart risk markers:
- Triglycerides (a type of blood fat) fell by about 40%.
- Blood pressure dropped by about 11 points.
- Waist size shrank by almost 7 inches.
- A marker of inflammation fell by more than half.
These are encouraging signs, but they aren’t the same as proof that the drug prevents heart attacks or strokes.
Side effects
Lilly says side effects were similar to other GLP-1 drugs. For this class, that usually means stomach issues like nausea, especially early in treatment.
One important detail
These main results only count people who stayed on the drug and didn’t start other weight-loss medicines. That approach shows how well the drug works when taken as directed. It can make results look better than what happens in everyday life, where some people stop treatment.
When could it be available?
Lilly plans to ask the FDA for approval in early 2027. Until then, retatrutide isn’t an approved medicine. Products sold online under that name aren’t regulated and may not contain what they claim. Meanwhile, competitors are working on their own triple-hormone drugs, though those are still in very early testing.
What does this mean for Canadians?
For Canadian readers, the most important thing about retatrutide’s headline-grabbing results may be the distance between a promising trial and a prescription you can actually fill. An FDA filing planned for early 2027 is a U.S. milestone, not a Canadian one. Health Canada runs its own review, and even an approval here tends to be the start of a longer wait while private insurers and provincial drug plans decide whether, and for whom, they’ll pay. Anyone who has tried to get coverage for Wegovy or Zepbound knows how that story often goes. That gap matters because the numbers are genuinely impressive: roughly a third of people on the top dose lost a quarter of their body weight. The findings are just as notable for what they don’t show, since the drug appears no better than existing options at controlling blood sugar, and it hasn’t yet been proven to prevent heart attacks or strokes. In the meantime, Canadians will almost certainly see “retatrutide” offered online by peptide sellers eager to cash in on the buzz. Those products are unapproved and unregulated, so there’s no guarantee they contain what the label says. The smarter move is patience, along with a conversation with your doctor about the proven treatments already available here.
Read more on this story here.
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