2026-08-06 13:07:33

The blockbuster weight-loss jab Mounjaro could dramatically reduce the risk of life-threatening heart attacks, according to a major new study.

Researchers found people taking the injection were a third less likely to suffer a heart attack than patients using another common type 2 diabetes treatment.

The findings add to growing evidence that GLP-1 weight-loss drugs may protect the heart as well as helping patients lose weight.

Scientists from Harvard University in Boston tracked almost 53,000 people with both type 2 diabetes and heart disease who were prescribed either Mounjaro, which contains tirzepatide, or the diabetes drug sitagliptin.

The team monitored major adverse cardiovascular events, known as MACE, including heart attacks, strokes and deaths from any cause.

After one year, 2.9 per cent of patients taking Mounjaro had experienced a major cardiovascular event, compared with 4.4 per cent of those taking sitagliptin.

Researchers estimated this equated to preventing one major cardiovascular event for every 70 patients treated.

The analysis also found Mounjaro reduced the risk of heart attacks by 33 per cent, although there was no significant difference in stroke rates between the two groups.

Patients taking the jab were also less likely to be admitted to hospital with infections, with one admission prevented for every 48 people treated.

In addition, the researchers estimated one death from any cause was prevented for every 122 patients taking Mounjaro.

Writing in The BMJ, the researchers said: “This study shows how trial-anchored evidence from clinical practice can estimate the expected cardiovascular benefit of initiating tirzepatide beyond standard background treatment and inform shared decision making.”

Previous research has shown semaglutide, the active ingredient in Wegovy and Ozempic, can lower the risk of serious heart problems, but this is among the first large studies to suggest tirzepatide may offer similar cardiovascular benefits.

Around four million people in the UK are estimated to be current or former users of weight-loss injections, although most obtain them privately.

GPs can currently prescribe Mounjaro for weight loss to people at the highest health risk, including those with severe obesity and multiple weight-related conditions such as high blood pressure, high cholesterol, type 2 diabetes and heart disease.

Heart disease affects around eight million people in the UK and causes about 170,000 deaths every year.

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