Weight loss injections may lower the risk of having a cardiac arrest, heart attack or stroke, but increase the risk of drug-induced pancreatitis, according to a new study.
Over the past few years, these types of drugs – known as GLP-1 agonists – have become more and more popular in the UK and around the world for weight loss.
While they were originally designed to lower blood sugar levels in people with type 2 diabetes, GLP-1 agonists also reduce your appetite, which means they can help people without diabetes lose weight too.
Some research also suggests that these medicines can reduce the risk of a range of diseases, including heart attacks and strokes.
However, there’s still a lot we do not know about how GLP-1 agonists affect different areas of the body.
To find out more, researchers behind a new study published in the journal Nature Medicine in January 2025 looked at the impact of taking GLP-1 agonists on 175 different diseases using health information from over 2.4 million veterans with type 2 diabetes across the United States.
They compared around 215,000 people with diabetes prescribed weekly injections of GLP-1 agonists to just over 1.2 million people who continued to receive their usual non-GLP-1 medicines to reduce blood sugar.
After an average of 3.68 years, people taking GLP-1 agonists had a lower risk of developing 42 different diseases than those given their usual medicines.
This included a 22 per cent lower risk of a cardiac arrest, 11 per cent lower risk of heart failure, 9 per cent lower risk of a heart attack and 7 per cent lower risk of ischaemic stroke.
As well as heart and circulatory diseases, people taking GLP-1 agonists were 24 per cent less likely to have liver failure, 22 per cent less likely to have respiratory failure and 12 per cent less likely to develop Alzheimer’s disease.
GLP-1 agonists were also linked to a lower risk of some mental health issues, such as substance use disorders, suicidal ideation and schizophrenia.
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However, people taking GLP-1 agonists also had a higher risk of 19 side effects or diseases compared to those receiving their usual medicines.
Most notably, they were nearly 2.5 times more likely to develop drug-induced acute pancreatitis, which is a serious condition where an organ called the pancreas becomes inflamed.
Other side effects included a 30 per cent higher risk of nausea or vomiting, 11 per cent higher risk of arthritis and a 6 per cent higher risk of low blood pressure.
What do the researchers say?
Previous research has already suggested GLP-1 agonists may increase or decrease the risk of many of the diseases included in this study.
For example, a study of 17,604 people published in 2023 in the New England Journal of Medicine found those given semaglutide (a type of GLP-1 agonist) had a 20 per cent lower risk of having a heart attack or stroke, or dying from coronary heart disease than those given a dummy injection after 2.75 years.
But researchers say that this new study shows these medicines can impact many different areas of both physical and mental health.
Senior author of the study, Clinical Epidemiologist Ziyad Al-Aly, told BBC news, “It was definitely eye-opening for me to see all these different hits in different organ systems”.
In the study, the researchers wrote that this may be because living with excess weight or obesity is a risk factor for many diseases, including heart attacks or strokes.
They also suggested that, as well as weight loss, GLP-1 agonists may reduce inflammation in the body, which could also lower the risk of several diseases.
How good was the research?
A key strength of the study was how large it was, with data from 215,970 people taking GLP-1 agonists, 1,203,097 people given their usual care and 1,072,154 given other medicines for diabetes.
However, all of these people had type 2 diabetes, and nearly 95 per cent were men, 80 per cent were aged over 60, and 70 per cent were white. This means the findings may have been different in other populations or for those only taking GLP-1 agonists for weight loss.
Also, the study was observational, which means it cannot prove GLP-1 agonists directly caused a lower or higher risk of the diseases in the study.
We also do not know what type of GLP-1 agonist people were taking in the study, and if the type they were taking had any effect on their risk of disease.
How good was the media coverage?
Many UK news outlets reported on the study, including the Daily Mail, The Telegraph, BBC, The Guardian and The Times, but their coverage was quite different.
While most headlines focused on the potential health benefits of weight loss injections, the Daily Mail’s highlighted the increased risk of pancreatitis: “Weight loss jabs DOUBLE risk of deadly condition, major study finds”.
And although The Telegraph’s headline focused on both the positive and negative findings, their article did not mention the important detail that all the people in the study had type 2 diabetes.
The BHF verdict
We know that obesity increases your risk of many diseases, including having a heart attack or stroke.
But we’re still learning more about taking GLP-1 agonists such as Wegovy for weight loss and how it could impact the risk of disease.
While this study does suggest these medicines may have a wide range of benefits, it also found that they can cause some serious side effects too.
If you’re thinking about taking weight loss injections, speak to your doctor for expert advice on whether they’re right for you.
Making changes to your lifestyle like eating a balanced diet with lots of vegetables, fruits, oily fish and beans, and regularly exercising can also help to manage your weight.
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