Eli Lilly's Tirzepatide Reduces Diabetes Risk and Achieves Long-Term Weight Loss in Three-Year Study

Eli Lilly and Company has shared comprehensive results from the Phase 3 SURMOUNT-1 study, the longest completed study of tirzepatide to date, spanning three years, which is 176 weeks. Weekly injections of tirzepatide, available as Zepbound® and Mounjaro®, in 5 mg, 10 mg, and 15 mg doses. Which, compared to placebo, significantly lowered the risk of type 2 diabetes progression in adults with prediabetes and obesity or overweight. Over the three years, tirzepatide led to a sustained average weight reduction of 22.9% at the 15 mg dose. These findings were published in “The New England Journal of Medicine (NEJM) and presented at ObesityWeek 2024.”

Ania Jastreboff, M.D., Ph.D., director of the Yale Obesity Research Center, said in a statement, "Individuals treated with tirzepatide lost on average up to 23% of their body weight and maintained this for over three years while benefitting from a substantial decrease in risk of developing type 2 diabetes. In absolute terms, nearly 99% of individuals treated with tirzepatide remained diabetes-free at 176 weeks. These results are impressive given the degree of sustained weight reduction and decreased risk of diabetes.”

Tirzepatide is the first approved medication that targets both GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) receptors, gut hormones involved in the body's incretin response to nutrient intake.

Jeff Emmick, M.D., PhD, senior vice president of product development at Lilly, also stated, "In the SURMOUNT-1 three-year study of tirzepatide, an average weight reduction of up to 22.9% was accompanied by a hazard ratio of 0.06 for progression to type 2 diabetes. This translates to a risk reduction of 94% and a number needed to treat nine to prevent one case of diabetes. These results underscore the critical role of long-term therapy with effective treatments like tirzepatide to achieve and maintain weight reduction."  

The study also showed that tirzepatide helped improve glycemic control, cardiometabolic factors like fasting insulin, blood pressure, and lipids, and health-related quality of life, with these benefits sustained through the 176 weeks. A post hoc analysis suggested that around half of tirzepatide's impact in delaying type 2 diabetes onset may be linked to weight loss, with other benefits possibly due to additional effects of the medication.

The safety profile of tirzepatide over 193 weeks (176 weeks on treatment plus a 17-week off-treatment follow-up) was consistent with previous reports from the 72-week SURMOUNT-1 data and other long-term studies. Other than COVID-19, the most common side effects were gastrointestinal, including nausea, diarrhoea, and constipation, which were generally mild to moderate in severity.