The FDA has flagged a possible link between these widely used medicines and a rare eye condition that can cause sudden vision loss, which may be permanent and following a review of available safety data, the regulator has decided that manufacturers of GLP-1 receptor agonist medicines must add a warning about this potential risk to their drug labels.
The condition is called Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION), while it is rare, its effects can be serious, as it damages the optic nerve, which carries visual information from the eye to the brain.
The warning does not mean that people taking these medicines will develop the condition, however, the FDA wants patients and doctors to be aware of the possible risk and know what symptoms to look out for.
NAION occurs when the blood supply to the optic nerve is reduced, resulting in damage that can affect a person's eyesight. One of its most concerning features is that it can cause sudden, painless vision loss in one eye.
A person may notice blurred vision, dark or missing patches in their field of vision, blind spots or difficulty seeing clearly. In some cases, the damage can be permanent.
The FDA has advised people experiencing sudden changes in their eyesight to seek immediate medical attention. Early medical assessment is important, particularly when vision loss happens without any pain.
The warning follows a detailed assessment of clinical trial data, animal studies, reports of side effects and other available research.
As part of its review, the FDA analysed 126 clinical trials involving 1,34,253 participants. Of these, 78,217 people received GLP-1 medicines, while 56,036 received a placebo or other comparator treatment.
The analysis identified 15 probable cases of NAION. Ten were reported among people taking GLP-1 medicines, while five occurred among those receiving placebos and no cases were identified among participants receiving other non-GLP-1 blood sugar-lowering medicines.
The incidence rate was found to be 6.4 cases per 1 lakh person-years among GLP-1 medicine users, compared with 3.8 cases per 1 lakh person-years in the comparator group.
These findings suggest a possible increase in risk, but they do not establish that the medicines directly cause NAION. The FDA also said that its review of animal data did not reveal a clear explanation of how these medicines could lead to the condition.
NAION is already a rare condition in the general population. However, certain health conditions can increase a person's risk of developing it, these include diabetes, high blood pressure, cardiovascular disease, high cholesterol, metabolic syndrome and obstructive sleep apnea.
This makes the latest warning particularly relevant for people taking GLP-1 medicines, as several of these conditions are also common among patients seeking treatment for obesity and diabetes.
The FDA has not advised everyone taking these medicines to stop their treatment. The warning highlights a potential risk and does not mean that the drugs will cause vision problems in every patient.
People should not stop or change their prescribed medication without speaking to their doctor, however, anyone who experiences sudden or unexplained changes in eyesight should get medical help immediately.
For patients diagnosed with NAION, the FDA recommends discussing whether the GLP-1 medicine should be discontinued with their healthcare provider.
The key takeaway for patients is to stay informed, watch for unusual changes in vision and discuss any concerns with their doctor rather than making changes to their treatment independently.