Medicines known as GLP-1 receptor agonists have become some of the most talked-about treatments in recent years.
Drugs such as semaglutide help people with type 2 diabetes lower blood sugar and often lead to weight loss. Researchers have also been studying whether these medicines influence the risk of other diseases beyond diabetes.
One question has been whether GLP-1 medicines affect the risk of age-related macular degeneration, a common eye disease that can cause severe vision loss in older adults. The most dangerous form is called neovascular age-related macular degeneration, or NVAMD, in which abnormal blood vessels grow under the retina and damage central vision.
Earlier studies produced conflicting results. Some suggested GLP-1 medicines might protect the eyes, while others hinted they could increase the risk of the disease. To provide a clearer answer, researchers from Johns Hopkins Medicine carried out a large international study.
The study was led by Dr. Cindy Cai and included medical records from 12 health databases in the Observational Health Data Sciences and Informatics network. The researchers analyzed anonymous records collected between 2017 and 2024 from hundreds of thousands of adults with type 2 diabetes.
They compared first-time users of semaglutide with people starting other diabetes medicines, including dulaglutide, exenatide, empagliflozin, sitagliptin and glipizide. All participants had previously taken metformin and had no recent history of GLP-1 medicine use.
The team used two different methods to identify patients who developed neovascular age-related macular degeneration. They then compared the chance of developing the disease while taking each medication.
The results were reassuring. People taking semaglutide did not have a higher or lower risk of developing NVAMD than people taking the other diabetes medicines. The same conclusion was reached using multiple statistical approaches.
The researchers also performed an analysis that compared patients with themselves during periods when they were taking medication and when they were not. Again, the results suggested no meaningful change in risk. The calculated risk ratios were very close to one, indicating no significant difference.
Dr. Cai said the findings help settle earlier disagreements in the scientific literature. However, she emphasized that the results apply only to adults with type 2 diabetes who started these medicines as diabetes treatment. The study cannot answer whether the same findings apply to people taking GLP-1 drugs mainly for weight loss.
The research was published in Ophthalmology. Because this was an observational study, it cannot prove cause and effect, but its very large sample size and careful design make the findings persuasive.
Overall, the study suggests patients with type 2 diabetes can be reassured that semaglutide and similar GLP-1 medicines do not appear to change the risk of this serious eye disease, although further research in other patient groups is still needed.
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Source: Johns Hopkins Medicine.
