Second study links Ozempic diabetes drug to doubled risk of rare eye condition

The widely used diabetes medication Ozempic, often utilized off-label for weight loss, has been linked to a rare but serious condition. Experts warn that the drug may cause a sudden loss of blood flow to the optic nerve, potentially leading to severe and irreversible vision loss.

Two large studies conducted by the University of Southern Denmark (SDU) have confirmed that the diabetes medication Ozempic is associated with a twofold increase in the risk of developing non-arteritic anterior ischemic optic neuropathy (NAION), a rare but serious eye condition. These findings, derived from extensive Danish and Norwegian health registers, align with concerns raised in a smaller American study last year.

NAION is caused by a sudden loss of blood flow to the optic nerve, potentially leading to severe and permanent vision loss. While the absolute risk remains low, the consistency of these findings highlights a concerning link between Ozempic and this condition.

Ozempic (semaglutide), approved for use in 2017 by the U.S. Food and Drug Administration (FDA), is a medication primarily prescribed for managing type 2 diabetes. Its use has grown rapidly due to its dual benefits of blood sugar control and significant weight loss, making it a popular choice among patients and healthcare providers.

Effective blood sugar control

Ozempic helps regulate blood sugar levels by mimicking the hormone GLP-1, which stimulates insulin production and reduces glucose release from the liver.

Weight loss

A significant benefit of Ozempic is its ability to aid in weight loss, making it particularly valuable for individuals with obesity-related health issues. By 2024, Ozempic gained widespread popularity among non-diabetic individuals seeking effective weight management solutions.

Reduced cardiovascular risks

Studies have shown that Ozempic reduces the risk of major cardiovascular events, such as heart attack and stroke, in patients with type 2 diabetes and preexisting heart disease.

Professor Anton Pottegård, lead author from SDU's Institute of Health Services Research, emphasized:

"We see more cases of NAION, a very rare but serious disease of the optic nerve, among users of semaglutide [Ozempic] than among users of other antidiabetic medications. While we don’t know why this happens, it seems the drug increases the risk of this disease."

Large-scale analysis

The first study analyzed the health records of 424,152 Danish patients with type 2 diabetes. It found that Ozempic users had double the risk of developing NAION compared to those on alternative diabetes treatments.

Specific patient groups

The second study, focusing on a smaller subset of patients and yet to undergo peer review, corroborated these findings. This research also identified a twofold increase in NAION risk among Ozempic users.

The researchers emphasize that their findings are not intended to discourage the use of Ozempic without medical consultation. While the drug poses a heightened risk of NAION, untreated diabetes often leads to other eye complications, such as diabetic retinopathy, which, although more common, is generally less severe than optic nerve damage.

The results underscore the need for informed discussions between patients and healthcare providers. Patients should weigh Ozempic’s benefits, such as improved blood sugar control and weight loss, against its potential risks.

These studies also call for increased vigilance among medical practitioners in monitoring eye health in patients taking Ozempic, particularly those at higher risk for vision-related conditions.

Further research is required to uncover the mechanisms behind Ozempic's link to NAION and identify populations most at risk of this rare complication.

Key findings from the Ozempic studies

Increased risk of NAION

Ozempic (semaglutide) doubles the risk of developing non-arteritic anterior ischemic optic neuropathy (NAION), a rare condition that damages the optic nerve.

The condition is caused by a sudden loss of blood flow to the optic nerve, potentially leading to severe and permanent vision loss.

The studies analysed comprehensive data from Danish and Norwegian health registers.

Findings corroborated earlier concerns raised in a smaller American study.

Despite the increased relative risk, the absolute number of NAION cases remains low, with 2 out of 10,000 Ozempic users developing the condition annually, compared to 1 out of 10,000 in the comparator group. Multiple analyses consistently showed a higher incidence of NAION among Ozempic users, though no direct causal link has been established. However, the observed correlation calls for further investigation.

Benefit-risk profile unchanged

Novo Nordisk, the manufacturer, stated that the studies do not alter the benefit-risk profile of semaglutide, emphasizing the very low annual incidence of NAION.

Potential implications and expert advice

Experts stress the importance of balancing Ozempic's benefits against its risks, highlighting the rarity of NAION while advising patients with potential eye problems to consult their physicians.

Most patients are encouraged to continue treatment under medical supervision. Regulators may investigate a potential causal link, which could lead to scrutiny of other drugs in the same class. Further research is needed to explore the prevalence of NAION among Ozempic users, understand the underlying mechanisms, and identify patients most at risk.

Previous studies

The concerns raised by the new Danish studies regarding Ozempic’s link to NAION are not entirely new. A smaller American study published last year also found that Ozempic more than doubles the risk of this rare optic nerve condition.

These earlier findings, though based on a smaller dataset, align with the larger-scale data from Denmark and Norway, suggesting a consistent pattern. The corroboration from multiple studies strengthens the validity of the observed association between Ozempic and the risk of NAION.

While the drug offers life-changing benefits for many, these findings underscore the importance of ongoing research and patient-specific risk assessments to ensure its safe use.