Could popular diabetes and weight-loss medicines increase the risk of permanent vision loss? The US Food and Drug Administration (FDA) has issued a safety warning about a possible link between GLP-1 receptor agonist drugs and a rare eye condition called non-arteritic anterior ischaemic optic neuropathy (NAION). However, Indian endocrinologists say the risk appears extremely small and advise patients not to panic or discontinue their medication without consulting their doctors.
In a drug safety communication issued on November 9, the FDA asked manufacturers of all GLP-1 receptor agonist medicines to include a warning about NAION in the “Warnings and Precautions” section of their product labels. The condition occurs when blood flow to the optic nerve is reduced, potentially causing sudden, painless vision loss in one eye. In some cases, the damage can be permanent.
FDA Reviews Evidence Linking GLP-1 Drugs to Vision Loss
GLP-1 medicines include widely prescribed drugs such as semaglutide (Ozempic, Wegovy and Rybelsus), liraglutide (Victoza and Saxenda), dulaglutide (Trulicity) and tirzepatide (Mounjaro and Zepbound). Doctors primarily prescribe these medicines to manage type 2 diabetes and obesity. Some also offer additional benefits in reducing cardiovascular and kidney-related risks.
To assess the potential eye-related risk, the FDA reviewed clinical trials, animal studies, post-marketing reports and observational research.
A meta-analysis of 126 clinical trials involving 134,253 participants identified 15 probable NAION cases. Of these, 10 occurred among people taking GLP-1 medicines, while five involved participants receiving a placebo. The estimated incidence stood at 6.4 cases per 100,000 person-years among GLP-1 users, compared with 3.8 cases among those receiving comparison treatments.
Additionally, the FDA identified a higher risk in a real-world comparison of GLP-1 users with patients taking DPP-4 inhibitors. However, researchers did not find a statistically significant increase when comparing GLP-1 medicines with SGLT-2 inhibitors. Importantly, the FDA clarified that the available evidence suggests a possible association but does not establish that GLP-1 drugs directly cause NAION.
Indian Endocrinologists Report Very Few Suspected Cases
Despite the FDA warning, Indian specialists say they have encountered very few suspected cases among patients taking these medicines.
Dr SK Wangnoo, Senior Consultant Endocrinologist, recalled a patient who experienced sudden blurred vision while taking a GLP-1 drug. Her vision returned completely to normal within a month after discontinuing the medication. Doctors restarted the treatment after three months, taking precautions to avoid a rapid fall in blood sugar levels. The patient has not experienced the symptom again.
Wangnoo said this was the only such episode he had encountered among thousands of patients treated in his practice. However, he noted that doctors still need to understand whether the eye changes resulted directly from the medication or from rapid changes in blood glucose levels.
He suggested that a sudden drop in blood sugar might contribute to these changes, although the exact relationship remains unclear. Similarly, endocrinologist Dr Ambrish Mithal said he had not encountered any confirmed NAION cases among his patients taking GLP-1 medicines. He cautioned against assuming that every episode of blurred vision indicates NAION. Describing the condition as a stroke of the optic nerve, he explained that it can cause irreversible damage.
Mithal noted that blurred vision can result from several conditions and stressed the importance of identifying the underlying cause. He also pointed out that the estimated incidence of 6.4 cases per 100,000 person-years among GLP-1 users was only marginally higher than the approximately four cases reported in the general population.
Therefore, he routinely recommends detailed eye examinations before prescribing these medicines and avoids them in patients considered to be at higher risk.
Benefits of GLP-1 Medicines Must Be Weighed Against Rare Risks
Dr Anoop Misra also reported encountering only one suspected NAION case among several thousand patients treated with GLP-1 medicines in his practice. He said the FDA warning deserves attention, but the potential risk remains extremely small. He also noted that European regulators have classified NAION as a very rare side effect of semaglutide, affecting up to one in 10,000 people.
According to Misra, doctors must consider this potential risk alongside the significant benefits of GLP-1 medicines in managing diabetes and obesity, as well as their protective effects on the heart, kidneys and liver.
When Should Patients Seek Medical Attention?
The FDA has advised patients taking GLP-1 medicines to seek immediate medical attention if they experience sudden, painless vision loss, blurred vision or blind spots.
Doctors should promptly refer patients with suspected NAION to an eye specialist. If the condition develops, they should also consider discontinuing the medication after evaluating the patient’s condition. However, specialists caution patients against stopping their diabetes or weight-loss treatment on their own. Instead, they should consult their treating doctor and undergo an appropriate eye examination if they notice any changes in vision.
NAION itself is uncommon in the general population. Published estimates range from 2.3 to 10.2 cases per 100,000 people annually among adults over 50.
Overall, while the FDA warning highlights a potential safety concern associated with GLP-1 medicines, Indian endocrinologists emphasise that the risk appears very low. Patients should remain alert to unusual visual symptoms, seek timely medical advice and continue treatment under medical supervision. As reported by thehindubusinessline.com, Indian endocrinologists have urged patients not to panic over the rare potential vision-loss risk associated with GLP-1 medicines, while emphasising the importance of timely eye examinations and medical consultation.