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Popular Weight Loss Drug Sold to Teens and Adults Linked to Higher Risk of Blindness

People who were prescribed Ozempic and Wegovy for weight loss or to treat Type 2 diabetes were more likely to develop an eye nerve injury resulting in blindness, but the doctors who conducted the study said more research is needed to establish a causal link.

JULY 9, 2024

People taking popular weight-loss drugs may be at increased risk of developing an eye nerve injury that can cause irreversible vision loss, according to a new peer-reviewed study.

Wegovy, a weight-loss drug, and Ozempic, a popular Type 2 diabetes drug also used for weight loss, contain the active ingredient semaglutide — a type of GLP-1 agonist developed by Danish drugmaker Novo Nordisk. Both drugs are available as weekly injections. Ozempic is also available in pill form.

After the U.S. Food and Drug Administration (FDA) approved Wegovy and Ozempic for adults in 2021 and 2017, respectively, the agency on Dec. 22, 2023, approved Wegovy for children 12 and up.

The two drugs attracted attention as celebrities — including Elon Musk and Chelsea Handler — in 2022 and 2023 talked about taking them, causing Novo Nordisk’s sales to skyrocket. The company’s most recent annual gross profits exceeded $30 billion.

Meanwhile, doctors at Massachusetts Eye and Ear and Brigham and Women’s Hospital — who on July 3 published their study in JAMA Ophthalmology — last summer noticed that an unusually high number of their patients taking semaglutide medications developed an eye condition called non-arteritic anterior ischemic optic neuropathy, or NAION.

This prompted the doctors to investigate whether there was a link between semaglutide prescriptions and NAION.

NAION is the second most common cause of blindness due to optic nerve damage (with glaucoma being the most common), the doctors wrote in their report. It can result in sudden vision loss in an eye due to loss of blood flow to the optic nerve.

The condition is permanent with no known treatment, NBC News reported.

The researchers’ data showed that people with diabetes were more than four times more likely to be diagnosed with NAION if they were taking semaglutide. Those who were overweight or obese were more than seven times more likely to experience the condition if they were taking the drug.

They said more research is needed before a causal link can be established.

The study was partially funded by a grant from Research to Prevent Blindness.

More research needed, doctors say

For the study, the doctors looked at six years of medical records from 16,827 patients in the Boston area, none of whom were initially diagnosed with NAION.

They focused on a subset of those patients — 1,689 individuals — who had diabetes or were overweight or obese. The doctors compared outcomes after 36 months in patients who were prescribed semaglutide to those who weren’t.

Semaglutide works by increasing insulin release, lowering the amount of glucagon released, delaying gastric emptying and reducing appetite.

The study did not look at how semaglutide might impact the optic nerve.

Of the 194 diabetes patients who were prescribed semaglutide, 17 developed NAION. Of the 361 obesity patients, 20 people developed the condition.

The findings suggest an association between semaglutide and NAION, the researchers said.

They called for more studies that could confirm or refute the association. “As this was an observational study, future study is required to assess causality,” they said.

They noted a few limitations of their study.

First, the medical records they analyzed came from a select patient sample seen at a hospital specializing in neuro-ophthalmology. “Therefore, our findings may not be fully generalizable to other settings,” they wrote.

Their study didn’t assess whether the patients actually took semaglutide as prescribed. “We did, however, confirm that prescribed doses of semaglutide were dispensed for all patients with NAION,” they wrote.

Also, their study didn’t fully assess if and how confounding factors — such as smoking — might have played a role in developing NAION.

Drugmaker responds

A Novo Nordisk spokesperson pointed out these limitations in an email to The Defender.

The spokesperson also said, “Semaglutide has also been studied in large real-world evidence studies and robust clinical development programs (SUSTAIN, PIONEER, STEP, SELECT, OASIS) with a cumulative exposure including from post-marketing use of over 22 million patient years.”

This totality of data “provides reassurance” of the drug’s safety profile, the Novo Nordisk spokesperson said.

The spokesperson added, “Patient safety is a top priority for Novo Nordisk, and we take all reports about adverse events from use of our medicines very seriously.”

Currently, Novo Nordisk is conducting a clinical trial to assess the long-term effects of semaglutide (1.0 milligram dosage) on diabetic retinopathy in patients with Type 2 diabetes.

The company — which has treated diabetes for decades, produces half the world’s insulin and was listed by Time magazine as one of the most influential companies of 2023 — expects to complete the trial in 2027, the spokesperson told The Defender.

Novo Nordisk’s Wegovy sales more than doubled between May 2023 and May 2024, raking in around $1.35 billion.

Roughly 90% of Novo Nordisk’s overall sales in 2023 came from its obesity and diabetes care division, which includes Ozempic and Wegovy.

List of side effects is growing

The Boston study is the latest in a series of medical publications highlighting possible health risks linked to semaglutide.

As The Defender previously reported, prior research suggested other serious side effects of GLP-1 agonist medications, including gastrointestinal problems, self-harm behavior, anesthesia complications and thyroid cancer.

Additionally, The Defender previously reported that America’s Poison Control Centers between January and November 2023 responded to nearly 3,000 calls — a more than 15-fold increase since 2019 — about semaglutide.

Many of the reports of semaglutide poisoning may have involved accidental overdoses, according to CNN.


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