Ozempic has become one of the most widely used medications for treating type 2 diabetes, helping millions of people control their blood sugar levels and improve their health.
However, new research suggests that the drug may be linked to a rare but serious eye condition that can cause sudden and permanent vision loss.
The findings come from two large studies conducted by researchers at the University of Southern Denmark.
The studies examined health records from Denmark and Norway and provide some of the strongest evidence so far that people taking Ozempic may have a higher risk of developing a condition known as non-arteritic anterior ischemic optic neuropathy, or NAION.
NAION is a disease that affects the optic nerve, which carries visual information from the eye to the brain. The condition occurs when blood flow to part of the optic nerve is suddenly reduced. Without enough oxygen and nutrients, the nerve becomes damaged. This can lead to sudden vision loss in one eye, and in many cases the damage is permanent.
Although NAION is considered uncommon, its effects can be life-changing. People often wake up with blurred vision or notice a sudden loss of part of their visual field. There is currently no proven treatment that can reverse the nerve damage once it occurs.
Concerns about a possible link between Ozempic and NAION first emerged after a smaller study in the United States reported that people taking the drug appeared to have more than double the risk of developing the condition.
Because the earlier study involved fewer patients, researchers wanted to see whether the findings would hold up in larger populations.
To investigate, the Danish and Norwegian research teams analyzed medical information from more than 424,000 people with type 2 diabetes. Among them, more than 106,000 people were using Ozempic, while the remaining participants were taking other diabetes medications.
The results showed a consistent pattern. People using Ozempic were approximately twice as likely to develop NAION compared with those using other diabetes treatments.
Professor Jakob Grauslund, an eye disease specialist involved in the research, noted that the number of NAION cases in Denmark has increased since Ozempic became widely available in 2018. Before the medication was introduced, Denmark typically recorded around 60 to 70 cases of NAION each year.
In recent years, the number has risen to around 150 cases annually, with most cases occurring among people with type 2 diabetes.
To ensure the findings were not simply due to differences between patients, another study led by Professor Anton Pottegård compared people who had recently started Ozempic with similar patients who had just begun other diabetes medications. This approach allowed researchers to compare groups with more similar health characteristics.
Once again, the results pointed in the same direction. Patients taking Ozempic had about twice the risk of developing NAION compared with those taking alternative treatments.
Despite these findings, experts emphasize that the condition remains rare. Even though the relative risk is higher among Ozempic users, the vast majority of people taking the medication will never develop NAION. For most patients, the benefits of controlling blood sugar and reducing the complications of diabetes still outweigh the risks.
Type 2 diabetes itself can damage blood vessels throughout the body, including those in the eyes. Poorly controlled diabetes increases the risk of blindness, kidney disease, heart disease, and other serious health problems.
For this reason, doctors stress that people should not stop taking Ozempic without first discussing the situation with their healthcare provider.
Researchers say the findings are most relevant for people who already have eye problems or who may be at higher risk of optic nerve disease.
For example, someone who has already experienced NAION in one eye could face a difficult decision. In such cases, doctors may consider switching to another diabetes medication to reduce the risk of damage to the remaining healthy eye.
The studies highlight the growing importance of personalized medicine. Different patients may benefit from different treatment plans depending on their medical history, overall health, and individual risk factors. Better understanding the possible side effects of medications helps doctors and patients make more informed decisions together.
Health authorities in Denmark and other countries have been informed about the findings. Researchers hope the results will encourage further investigation into the relationship between Ozempic and eye health. Additional studies may help determine why the increased risk occurs and whether certain groups of patients are more vulnerable than others.
For now, experts recommend that people taking Ozempic remain aware of any sudden changes in their vision. Symptoms such as unexpected vision loss, blurred vision, or dark areas in the visual field should be treated as a medical emergency and assessed by a healthcare professional as soon as possible.
The research was published in the International Journal of Retina and Vitreous and was also released as a preprint on medRxiv. While more research is needed, the studies provide important information about a rare but potentially serious side effect that patients and doctors should consider when making treatment decisions.
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