Semaglutide, the active ingredient in weight-loss medications Ozempic and Wegovy, may be associated with an increased risk of an eye condition that causes vision loss, a new study suggests.
Researchers at the Harvard School of Public Health have drawn a link between Ozempic and the likelihood of developing nonarteritic anterior ischemic optic neuropathy (NAION), known for causing sudden vision loss in one eye due to reduced blood flow to the optic nerve. People with diabetes face a heightened risk of developing the rare disease.
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Novo Nordisk, the pharmaceutical firm that produces the drugs, has said the study's data does not confirm any causal association between semaglutide and the condition, and the study authors admitted more research was needed.
The study used eye clinic patient data to identify 710 people treating type 2 diabetes and 979 people treating obesity, either with semaglutide or an entirely different medication.
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It found that, over a three-year period, 8.9 percent of diabetes patients using semaglutide were diagnosed with NAION, compared to 1.8 percent of those on another medication.
Among the overweight and obese group, the risk for developing the eye condition was 6.7% compared to 0.8% for the other medication group.
A spokesperson for pharmaceutical firm Novo Nordisk told Newsweek: "Patient safety is a top priority for Novo Nordisk, and we take all reports about adverse events from the use of our medicines very seriously. Overall, the data published in the study is not sufficient to establish a causal association between GLP-1RA [semaglutide] use and NAION.
"NAION is not an adverse drug reaction for the marketed formulations of semaglutide. Semaglutide has been studied in large, real-world evidence studies and robust clinical development programs with a cumulative exposure over 12 million patient years. The totality of data provides reassurance of the safety profile of semaglutide."
Semaglutide is currently being examined in a clinical trial being conducted by Novo Nordisk to assess the long-term effects of semaglutide 1mg on diabetic retinopathy in patients with type 2 diabetes with an expected completion date in 2027.
The Danish pharma giant added that there are key measurement limitations in the study, which need to be considered while interpreting the findings.
For instance, it does not provide information on the semaglutide dose at initiation and end of treatment. In addition, confounders such as smoking, duration of diabetes and optic disc morphology were not considered in the analysis.
"This is an interesting report of a potential negative consequence of prescribing the GLP-1 agonist drug semaglutide for those with diabetes, on their risk of NAION, a cause of blindness. Compared to those prescribed other drugs for diabetes, those who received semaglutide had a greater risk of NAION after three years," Margaret Morris, professor of pharmacology from the School of Biomedical Sciences at Australia's University of New South Wales, said in a statement.
"The authors sound a warning that the drug may increase risk of this condition, while pointing out that more work is required to confirm any association. It is noteworthy that the group prescribed semaglutide was older than the other group, but the authors suggest the risk was not related to baseline differences."
While the researchers acknowledge these findings do not show semaglutide causes this increase in risk, they emphasize the need for further research to better understand the correlation.
"The study points out that the retrospective nature of the research design does not permit causality to be determined, and is careful to add various caveats to their findings. The researchers call for a larger study with well described optic neuropathy diagnostic criteria to assess whether there is a casual link between eye disease and semaglutide use," Morris added.
The most common side effects of Ozempic, according to Novo Nordisk's website, are nausea, stomach pain, constipation, diarrhea and vomiting.
Update 4/7/2024 5:30 a.m. ET: This headline has been changed.
Update 4/7/2024 5:47 a.m. ET: This article has been updated with a link to the research paper.
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Isabel Cameron is a Science Reporter at Newsweek, based in London, U.K. She has covered a range of health topics ... Read more
