GLP-1 receptor agonists are changing the treatment of type 2 diabetes. These medicines copy the action of a natural hormone that helps control blood sugar, slows stomach emptying and reduces appetite.
Millions of people now take drugs such as semaglutide for diabetes, and many also use them for weight management.
As the use of these medicines has expanded, scientists have investigated whether they influence diseases outside the pancreas. One concern has involved neovascular age-related macular degeneration, a fast-moving eye disease that can destroy central vision if left untreated.
Previous research has pointed in different directions, leaving doctors uncertain. Some reports suggested GLP-1 drugs might reduce the risk of eye disease, while others reported the opposite. Researchers at Johns Hopkins Medicine wanted to examine the question using much larger datasets.
The investigators reviewed health records from more than 800,000 first-time users of several diabetes medicines across 12 international health databases. The study focused on adults with type 2 diabetes who began a second-line treatment after metformin.
Semaglutide users were compared with people taking other GLP-1 medicines as well as several non-GLP-1 diabetes drugs. The researchers tracked who later developed neovascular age-related macular degeneration using validated medical records and treatment codes.
No matter which analytical method was used, semaglutide users showed a similar risk of developing NVAMD compared with the other treatment groups. The differences observed were so small that they could easily have occurred by chance.
The scientists also looked only at patients who eventually developed the eye disease and compared their risk during periods on and off medication. This second analysis reached the same conclusion, with risk ratios remaining close to one, meaning there was no measurable increase or decrease in risk.
Lead investigator Dr. Cindy Cai said the goal was to resolve the confusion created by earlier studies. She stressed that the findings should not automatically be applied to people without type 2 diabetes or to those taking GLP-1 medicines mainly for obesity treatment.
The study highlights the importance of testing drug safety in very large populations before drawing conclusions from smaller reports. It also reminds patients not to stop prescribed medicines because of isolated headlines without discussing concerns with their doctor.
The findings were published in the journal Ophthalmology. Although observational studies cannot completely rule out hidden factors, this investigation included a remarkably large number of patients and several independent analyses that reached the same conclusion.
Taken together, the evidence suggests semaglutide and related GLP-1 medicines neither raise nor lower the risk of neovascular age-related macular degeneration in adults with type 2 diabetes, while further studies are needed in other populations.
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Source: Johns Hopkins Medicine.
