Happy Tuesday! There may be a new, unintended side effect linked to Novo Nordisk's blockbuster diabetes injection, Ozempic.
Danish health authorities on Monday said they are asking the European Union's drug regulator to review the findings of two Danish studies linking Ozempic to an increased risk of a rare vision-threatening eye condition in Type 2 diabetes patients.
The condition is called non-arteritic anterior ischemic optic neuropathy, or NAION. It is characterized by vision loss due to decreased blood flow to the front part of the optic nerve, which connects the eye to the brain.
The disease typically occurs without any pain and most commonly affects people ages 50 and above. NAION affects between 2.3 and 10.3 patients per 100,000 people per year in the U.S., according to some estimates.
The Danish Medicines Agency said it has kept close tabs on NAION as a possible adverse effect of semaglutide, the active ingredient in Ozempic, over the last six months. The agency received 19 reports of the condition in Denmark as of Dec. 10.
But the overall number of NAION cases in Denmark has increased since Ozempic was introduced in the Danish market in 2018, Jakob Grauslund, professor in eye diseases at the University of Southern Denmark, or SDU, said in a release Monday. Denmark used to see around 60 to 70 cases a year but now has up to 150, added Grauslund, who helped conduct one of the studies.
It's the latest potential concern about popular GLP-1s such as Ozempic, which mimic gut hormones to regulate blood sugar and tamp down appetite. Demand for the drug class has soared despite hefty price tags and a handful of unpleasant side effects that are most commonly gastrointestinal, such as nausea and vomiting.
In a statement Monday, Novo Nordisk said after a "thorough evaluation of the studies" and an internal safety assessment, the Danish drugmaker is "of the opinion that the benefit-risk profile of semaglutide remains unchanged." The company added that patient safety was a top priority.
The studies, conducted independently by SDU researchers and other institutions, both found that diabetes patients who used Ozempic were more than twice as likely to be diagnosed with the condition than those who took another diabetes drug.
The first Danish study was based on data from more than 400,000 diabetes patients, a quarter of whom were treated with Ozempic and the rest with other diabetes drugs. The second study involved data from more than 44,000 Danish diabetes patients who received Ozempic between 2018 and 2024 and nearly 17,000 Norwegian patients who took the drug between 2018 and 2022.
The studies were posted on medRxiv, a website that posts studies before they've been reviewed by outside scientists. Both appear to confirm a link first suggested in a Harvard University study earlier this year.
Still, the authors of the first SDU study said that the absolute risk of the condition among semaglutide users is low. They added that assuming the risk remains constant over time, the results indicate that a diabetes patient taking Ozempic for 20 years would have a 0.3% to 0.5% chance of developing NAION.
"Although our findings thereby do not rule out the possibility of an increased risk of NAION when using semaglutide for obesity, the low number of observed events suggests that any potential risk is likely of limited absolute magnitude," the authors of the first study said.
They added that additional analyses that are designed differently are needed to further investigate whether Wegovy users, who take semaglutide for obesity, also have an increased risk of the condition.
For now, analysts are less concerned about the risk of NAION and its potential to reduce prescriptions of Ozempic.
"Unless semaglutide is found to be unique among GLP-1s in harboring this risk, prescribing [is] not likely to be affected," TD Cowen analyst Michael Nedelcovych said in a research note on Monday.
