An emerging weight-loss drug could help some obese people with type 2 diabetes shed up to a quarter of their body weight, while keeping blood sugar under control, a clinical trial has found.
Retatrutide works by mimicking three different hormones to control hunger and blood sugar, as well as speeding up metabolism.
It differs from other GLP-1 (glucagon-like peptide-1) drugs as the latter only mimic one or two different hormones.
The trial, known as Triumph-2, took place at 92 sites in eight countries, with more than 2,000 patients taking part.
All had a body mass index (BMI) of more than 27 and type 2 diabetes.
Some 1,152 patients were prescribed retatrutide, ranging from 4mg to 12mg, or a placebo.
After 80 weeks, those on 4mg of retatrutide lost 11.9% of their body weight on average.
This increased to 16.8% with 9mg and 18.8% with 12mg.
Those in the placebo group lost 5.1% on average.
At the 12mg dose, almost half (47%) of patients lost at least 20% of their starting weight and 31% lost at least a quarter.
This is compared with 6% and 3% respectively, in the placebo group.
Elsewhere, almost three-quarters (72%) achieved an HbA1c of 6.5% or lower – the standard threshold used by many health experts to diagnose diabetes – compared with 29% on placebo.
The most frequently reported side effects during the study were diarrhoea and nausea.
There were also seven deaths – two in the retatrutide 4mg group, three in the 9mg group, one in the 12mg group, and one in the placebo group.
However, these were deemed unrelated to the study intervention by the investigator.
The researchers said the trial suggests “retatrutide may advance the treatment of obesity and type 2 diabetes, a population where weight reduction has been challenging to achieve”.
They added: “Retatrutide demonstrated substantial reduction in body weight, alongside improvements in blood sugar control and cardiometabolic risk factors, with a safety profile generally similar to other molecules with GLP-1 receptor agonist activity.
“These findings support obesity treatment as a strategy for people with obesity and type 2 diabetes.
“Further studies are required to determine whether these benefits translate to improvements in other obesity-related complications.”
The findings were presented on Sept 30 (2026) at the annual meeting of the European Association for the Study of Diabetes (EASD) in Milan, Italy, and published Oct 1 (2026) in The Lancet medical journal.
Meanwhile, a separate study being presented at EASD found the investigational drug petrelintide helped people lose more than 10% of their body weight, but with fewer side effects.
The once-weekly injection mimics the natural pancreatic hormone amylin to make patients feel fuller faster.
Researchers suggest it could benefit those who cannot tolerate GLP-1 drugs.
The trial took place across 32 sites in the United States, Poland and Romania, and included 485 people who were given either petrelintide or a placebo.
Those prescribed the drug were given doses ranging from 1mg to 9mg.
Mean weight loss in body fat percentage was 8.7% for the lowest dose and 10.2% for the highest.
The most common side effect was nausea, with the trial finding the “vast majority” of patients were able to escalate to the highest doses.
The researchers said “amylin-based therapies for obesity might substantially improve tolerability and overall patient experience, and potentially drive greater treatment adherence”. – By Storm Newton/PA Media/dpa
