Real-world data shows Novo Nordisk’s semaglutide outperforms Eli Lilly’s tirzepatide on cardiovascular outcomes 

Data from the STEER study, presented at the European Society of Cardiology (ESC) Congress 2025, suggest Wegovy^® (semaglutide) significantly reduced the risk of major cardiovascular events (MACE) compared with Eli Lilly’s tirzepatide in people with obesity and cardiovascular disease. 

Novo Nordisk has reported that Wegovy reduced the risk of heart attack, stroke, or death by 57% compared with tirzepatide in patients with obesity and cardiovascular disease, based on findings from the STEER real-world study. The analysis examined health insurance claims from more than 21,000 US patients in the Komodo Research database who began treatment with either drug from May 2022. After propensity score matching, 10,625 people were included in each group, all aged 45 years or older with overweight or obesity and established cardiovascular disease, but no diabetes. 

Key findings 

Among patients who remained continuously on treatment, without gaps of more than 30 days, Wegovy users had a 57% greater reduction in the risk of MACE compared with those on tirzepatide. Events were rare, recorded in 15 patients (0.1%) on Wegovy versus 39 patients (0.4%) on tirzepatide, over an average follow-up of 3.8 and 4.3 months, respectively. 

When including all treated patients, regardless of treatment gaps, Wegovy was associated with a 29% lower risk of MACE. Over an average follow-up of just over 8 months, 56 cardiovascular events (0.5%) were observed in Wegovy users compared with 83 events (0.8%) in the tirzepatide group. 

Anna Windle, Senior Vice President of Clinical Development, Medical and Regulatory Affairs at Novo Nordisk, commented:  

“In the STEER study, patients using Wegovy had greater cardiovascular improvements compared to tirzepatide, indicating that the same CV benefit cannot be generalized across other molecules in the GLP-1 or GIP/GLP-1 classes and may come specifically from the semaglutide molecule.” 

Implications for the GLP-1 market 

The results build on earlier randomized trial evidence, notably the SELECT trial, which demonstrated Wegovy’s superiority over placebo in reducing cardiovascular events. They also align with the SCORE real-world study, which found lower event rates among Wegovy users compared with non-users in routine practice. 

Novo Nordisk stressed the role of real-world data (RWD) in complementing randomized controlled trials (RCTs), while noting study limitations such as short follow-up, few cardiovascular events, and possible coding inaccuracies.  

Market context 

The findings come during a difficult period for Novo Nordisk, which has faced declining US market share, competition from Eli Lilly’s tirzepatide-based products Zepbound and Mounjaro, and policy uncertainty linked to White House tariff measures. Despite this, Wegovy recently became the first GLP-1 approved by the US FDA to reduce the risk of major cardiovascular events in people with obesity and heart disease. 

In the UK, supply issues have also been a concern. Widespread shortages of semaglutide and other medicines affected patient access through 2023 and 2024, with prescribing restricted to those already on treatment. By early 2025, supplies of Ozempic, Rybelsus, and Mounjaro had stabilized, though health authorities continue to advise that GLP-1s be prescribed only for licensed indications. The World Health Organization has also warned about counterfeit semaglutide products circulating in the UK. 

Market analysts suggested the STEER data may provide some momentum for Novo Nordisk. Michael Field, Chief Equity Strategist at Morningstar, said the results could be a potential “game changer” but added that investors remained “encouraged, but not getting carried away.” 

Broader health impact 

Cardiovascular disease remains the leading global cause of death, responsible for nearly 21 million deaths each year. Obesity is a major contributor, with 2 in 3 obesity-related deaths linked to cardiovascular complications. 

As Windle highlighted: 

“Real-world studies, like STEER, provide us with important insights into how treatments may serve patients outside of controlled clinical trials as we continue to learn more about the benefits of Wegovy beyond weight management.”