Semaglutide has become one of the world’s best-known medicines for treating type 2 diabetes and helping people lose weight.
Sold under brand names such as Ozempic and Wegovy, it has helped millions of people control blood sugar, lose weight, and lower their risk of some heart problems.
However, a new study suggests that the medicine may also have an important eye risk that patients and doctors should not ignore. The research was published in JAMA Ophthalmology.
Researchers from the University of Toronto found that older adults with diabetes who used semaglutide or similar medicines were more likely to develop a serious eye disease called neovascular age-related macular degeneration, or nAMD.
This condition is one of the leading causes of severe vision loss in older adults in Western countries. Although it is less common than the dry form of macular degeneration, it can damage vision much more quickly.
Age-related macular degeneration affects the macula, the small central part of the retina that allows people to read, recognise faces, and see fine detail. In the neovascular form, abnormal blood vessels grow beneath the retina and leak blood or fluid. This damages the macula and can lead to permanent loss of central vision if it is not treated promptly.
Semaglutide belongs to a group of medicines known as GLP-1 receptor agonists. These drugs have changed diabetes treatment because they help lower blood sugar, reduce appetite, and often lead to significant weight loss. They have become increasingly popular in recent years, but scientists have continued to study their long-term safety.
Earlier clinical trials had already raised some questions about eye health. Studies including SUSTAIN 6 and PIONEER 6 reported more diabetic eye complications in some people taking semaglutide. There have also been a small number of reports of optic nerve damage, while other laboratory studies suggested the medicine might actually protect the eyes. As a result, the evidence remained uncertain.
In the new study, researchers analysed health records from 139,002 adults aged 66 years and older in Ontario, Canada, between 2020 and 2023. All participants had diabetes. More than 46,000 had taken semaglutide or similar GLP-1 medicines for at least six months, while the remaining participants had not used these medicines.
The researchers found that people using GLP-1 medicines had more than twice the risk of developing neovascular age-related macular degeneration compared with non-users. The risk also appeared to increase with longer use. People who had taken the medicine for more than 30 months were more than three times as likely to develop the condition.
The study also found that older age and a previous history of stroke or diseases affecting blood vessels in the brain further increased the risk. Although the findings are concerning, the researchers emphasise that the study does not prove that semaglutide directly causes the eye disease. Other factors related to diabetes or overall health could also play a role.
The researchers believe more studies are needed to understand exactly why this link exists. In the meantime, they suggest that people taking semaglutide, especially for long periods, should have regular eye examinations so any vision problems can be detected and treated as early as possible.
The benefits of the medicine remain important for many patients, but careful monitoring may help reduce the risk of permanent vision loss.
The study was published in JAMA Ophthalmology.
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