- A phase 3 trial found that retatrutide significantly reduced HbA1c and body weight in adults with type 2 diabetes.
- The weekly injection acts on three hormone pathways, GLP-1, GIP and glucagon.
- The results are promising, but the study compared retatrutide with placebo rather than directly against Ozempic, Wegovy or Mounjaro.
A new weekly injection for type 2 diabetes has shown strong results in a phase 3 trial.
The drug, retatrutide, is designed to lower blood sugar, reduce appetite and increase energy expenditure.
It works differently from current GLP-1 drugs because it targets three hormone pathways.
These are GLP-1, GIP and glucagon.
Ozempic and Wegovy mainly target GLP-1, while Mounjaro targets GLP-1 and GIP.
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Retatrutide adds glucagon receptor activity, which may help the body burn more energy.
In the trial, 930 adults with type 2 diabetes were randomly assigned to receive weekly retatrutide or placebo.
None were already taking diabetes medicines.
All had inadequately controlled blood sugar and a body mass index of at least 23.
After 40 weeks, people taking retatrutide had average HbA1c reductions of around 1.7 to 1.9 percentage points.
That compared with a 0.8 percentage point fall in the placebo group.
Weight loss was also substantial.
Participants taking retatrutide lost around 11.5% to 15.3% of body weight, compared with 2.6% on placebo.
Cholesterol and blood pressure also improved in those taking the drug.
Most side effects were mild to moderate and tended to ease over time.
As with other drugs in this class, gastrointestinal symptoms were the most common issue.
That usually means nausea, diarrhoea, constipation or vomiting.
The results are encouraging, especially for people living with both type 2 diabetes and obesity.
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But there is an important caveat.
This study compared retatrutide with placebo, not with semaglutide or tirzepatide.
So it cannot prove from this trial alone that retatrutide is better than existing treatments.
Head-to-head trials will be needed.
Even so, the data suggest triple-action drugs may become a major next step in diabetes and obesity care.
