FDA flags potential vision loss risk linked to GLP-1 drugs: What users of weight-loss medications should know

The US Food and Drug Administration (FDA) has warned of a potential increased risk of a rare eye condition that can cause sudden and permanent vision loss among patients taking glucagon-like peptide-1 receptor agonist (GLP-1 RA) medications, widely used to treat type 2 diabetes and obesity.

The condition, known as non-arteritic anterior ischemic optic neuropathy (NAION), can cause sudden, painless loss of vision in one eye. The FDA said patients may experience acute vision impairment, including permanent vision loss, and urged those taking these medications to watch for symptoms.

Following a comprehensive safety review, the agency is requiring manufacturers of all GLP-1 RA medications to include information about the potential increased risk of NAION in the 'Warnings and Precautions' section of their product labels.

GLP-1 drugs mimic the action of a natural hormone released by the intestine. The hormone helps regulate blood sugar levels after meals and acts on parts of the brain responsible for controlling appetite and food intake.

These medications are widely prescribed to people with type 2 diabetes and those seeking to reduce excess body weight and maintain long-term weight loss. Certain drugs in the class are also approved to reduce the risk of major cardiovascular events, including heart attacks, strokes and death, in eligible adults.

Other approved uses include reducing the risk of worsening kidney disease in certain patients with type 2 diabetes, treating moderate to severe obstructive sleep apnoea in adults with obesity, and treating metabolic dysfunction-associated steatohepatitis (MASH) with moderate-to-advanced liver scarring.

What is NAION and what are its symptoms?

NAION occurs when blood flow to the front portion of the optic nerve, known as the optic disc, is reduced. Although the exact underlying cause is not fully understood, the condition can lead to sudden vision impairment.

According to the FDA, symptoms may include sudden, painless vision loss in one eye, which patients may first notice upon waking up. Other warning signs include blurred vision, blind spots, tunnel vision, distortion of colours and reduced central visual sharpness, including hazy or blurry patches.

The agency has advised patients to contact their healthcare professionals immediately if they experience any of these symptoms.

Patients who have experienced a NAION event should discuss with their doctors whether to continue taking their GLP-1 RA medication or discontinue treatment.

How significant is the risk?

The FDA's analysis of 126 randomised controlled clinical trials involving 134,253 participants found a higher incidence of NAION among patients treated with GLP-1 RAs compared with those receiving a placebo or other non-GLP-1 blood sugar-lowering medications.

The analysis identified 15 probable NAION cases, including 10 among GLP-1 RA users and five among patients receiving a placebo. No cases were identified among participants receiving other non-GLP-1 RA glucose-lowering medications.

The incidence rate was 6.4 cases per 100,000 person-years among GLP-1 RA users, compared with 3.8 cases per 100,000 person-years among those in the comparator group.

For context, the reported incidence of NAION in the general population is between 2.3 and 10.2 cases per 100,000 people annually among adults above the age of 50, based on published literature.

The FDA also conducted a retrospective study using its Sentinel Real-World Evidence Data Enterprise, examining adults with type 2 diabetes who started GLP-1 RAs or other commonly prescribed diabetes medications between 2019 and 2024.

The study found NAION incidence rates of 30-32 cases per 100,000 person-years among GLP-1 RA users, 31 among those taking SGLT-2 inhibitors and 26 among patients receiving DPP-4 inhibitors.

While the study did not find a statistically significant increase in NAION risk among GLP-1 RA users compared with SGLT-2 inhibitor users, it found an increased risk compared with patients taking DPP-4 inhibitors.

What should patients and doctors know?

The FDA said NAION cases have been reported across all currently marketed GLP-1 RA products. It also noted that people with a history of NAION face an increased risk of recurrence, while those who have experienced the condition in one eye are at greater risk of developing it in the other eye.

Other potential risk factors include smoking, diabetes, high blood pressure, sleep apnoea, anaemia and kidney disease.

The agency has advised healthcare professionals to inform patients about the potential risk and instruct them to immediately report sudden, painless vision loss, visual field defects or other visual disturbances in one eye.

Doctors should promptly refer patients suspected of having NAION to an ophthalmologist for evaluation. They should also consider discontinuing GLP-1 RA treatment in patients who develop the condition, unless the benefits of continuing treatment clearly outweigh the risks.