CATEGORY: DIET & WEIGHT
Retatrutide, a weekly shot that leans on three hormones at once, cut body weight by an average of 18.8% at its highest dose in adults with type 2 diabetes and obesity. That figure covers all 80 weeks of the trial and everyone assigned to the dose, including people who stopped their shots along the way. Placebo came in at 5.1%. Blood sugar fell with the weight: HbA1c, the standard three-month average of blood sugar, dropped by up to 1.6 points against 0.2 on placebo.1
One Drug, Three Hormone Signals
Most weight-loss injections imitate one gut hormone, GLP-1, or pair it with a second. Retatrutide adds a third, acting on GLP-1, GIP and glucagon receptors together, which both quiets appetite and nudges the body to burn more energy. The trial behind the new numbers, called TRIUMPH-2, enrolled 1,152 adults at 92 clinics in eight countries. All of them had type 2 diabetes plus obesity or overweight. The average participant arrived with an HbA1c of 7.7% and a BMI of 38, and 92% were already taking at least one glucose-lowering medication. Each received weekly shots for 80 weeks: retatrutide building up to 4, 9 or 12 mg, or a placebo. Neither the participants nor their doctors knew who had the real drug. Doses climbed gradually, a step every four weeks, the usual way to soften this drug class’s stomach effects.
Half the Top-Dose Group Lost a Fifth of Their Weight
On the 12 mg dose, 52% of participants lost at least a fifth of their body weight. On placebo, 1.5% did. People who stayed on the highest dose through the end averaged a 20.8% loss, which worked out to 49.6 pounds. By week 80, 59.5% of that group no longer measured as obese on the BMI scale. The diabetes side kept pace. Roughly four in five participants on the two higher doses finished with an HbA1c of 6.5% or below, the level commonly used to diagnose diabetes, while about one in four got there on placebo. Systolic blood pressure, the top number in a reading, fell by 10.8 mmHg on the top dose.
The Price Was Paid Mostly in the Stomach
Side effects looked familiar for this family of drugs. Up to a third of participants had diarrhea and up to 28% had nausea, against 13% and 8% on placebo. A tingling or crawling skin sensation called dysesthesia, an oddity reported with retatrutide before, affected up to 7%, and episodes of low blood pressure reached 6%. Quitting over side effects ranged from about 4% on the lowest dose to 12% on the middle one, with 5% on placebo. Most of what people felt was rated mild or moderate.
Why Diabetes Set a Higher Bar
Obesity drugs have a long record of underperforming in people with type 2 diabetes. Tirzepatide, the strongest option now approved, produced a 14.7% average loss at its top dose in its own 72-week diabetes trial, with 3.2% on placebo.2 The lead investigator of the new trial said treating the two conditions together has always been a challenge, and that gap is exactly what this study was built to test. One caution belongs beside the result. Retatrutide isn’t approved anywhere yet, so nobody can be prescribed it today, and Eli Lilly, which makes the drug, paid for the trial. The company says it plans to seek approval in 2027. A companion trial of the same drug in people with obstructive sleep apnea is due to report separately, which will show whether the pattern holds beyond diabetes.
Key Takeaways
- At the highest dose, average weight loss reached 18.8% of body weight over 80 weeks counting everyone assigned to the drug, and 20.8% among those who stayed on it. Placebo came in near 5%.
- About four in five people on the two higher doses ended with long-term blood sugar at or below the usual diabetes threshold, compared with roughly one in four on placebo.
- Digestive side effects were common, and about one person in ten on the middle dose stopped treatment because of them.
- The drug is still experimental. It can’t be prescribed, and its maker funded the trial.
References
- Bellido V, le Roux CW, Ekinci EI, et al. Retatrutide in adults with obesity and type 2 diabetes (TRIUMPH-2): a double-blind, parallel-group, randomised, placebo-controlled, phase 3 trial. The Lancet. 2026;S0140-6736(26)01861-1. link
- Garvey WT, et al. Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes (SURMOUNT-2): a double-blind, randomised, multicentre, placebo-controlled, phase 3 trial. The Lancet. 2023;402(10402):613–626. link