Phase 3 trial results indicate that a new weekly triple-action injection for type 2 diabetes can substantially lower blood sugar and body weight. Over 40 weeks, participants given retatrutide lost more than four times the weight of those on placebo, while their average reduction in long-term blood sugar (HbA1c) was more than double that seen with placebo. The medication mimics three gut hormones—GLP-1, GIP and glucagon—that regulate appetite, blood sugar and metabolism. It differs from treatments such as Ozempic and Wegovy, which mainly act on GLP-1, and from Mounjaro, which targets GLP-1 plus GIP. Retatrutide additionally activates the glucagon receptor to raise energy use. In the Lancet study, 930 adults with type 2 diabetes who were not on other diabetes drugs received either 4 mg, 9 mg or 12 mg of retatrutide or placebo. All had poorly controlled blood sugar and a BMI of at least 23. Researchers tracked HbA1c, weight, cholesterol and side effects. After 40 weeks, HbA1c fell 1.7–1.9 percentage points with retatrutide versus 0.8 with placebo. Body weight dropped 11.5–15.3 percent on the drug compared with 2.6 percent on placebo. Cholesterol and blood pressure also improved. Fourteen people had serious adverse events, two of them in the placebo group. Most side effects were mild or moderate, mainly gastrointestinal, and lessened over time. The authors note the drug could offer greater weight loss for patients needing stronger treatment. Additional trials are under way. Earlier manufacturer data showed strong weight reduction in people with obesity. Experts called the results encouraging but stressed that medicines are not a complete solution and that prevention remains essential. They also noted the need for head-to-head studies and support to maintain nutrition and muscle mass.
