Summary

Diabetes increases the risk of developing open-angle glaucoma by about 36%, although it does not directly cause it. High blood sugar can damage the optic nerve through inflammation, oxidative stress, and increased eye pressure. Diabetes can also directly cause a rarer, more aggressive form called neovascular glaucoma, which can lead to sudden pain and vision loss. Regular dilated eye exams and good blood-sugar management are important for detecting glaucoma early and slowing its progression.

Doctor, I Have a Question: What is the Relationship Between Glaucoma and Diabetes?

 

Question answered by
Gregory K. Harmon, MD
Board Chairman,
The Glaucoma Foundation

 

Diabetes doesn’t directly cause the most common form of glaucoma, open-angle glaucoma, but it significantly raises your risk. An analysis of prospective studies found that people with diabetes are 36% more likely to develop open-angle glaucoma compared to people without diabetes.

Diabetes affects the eyes in many ways, especially the retina and its blood supply. The relationship with glaucoma is complex: high blood sugar creates conditions in the eye that make glaucoma more likely to develop and harder to control once it does.

For diabetics with open-angle glaucoma — the type responsible for most cases, several overlapping processes accelerate damage to the optic nerve. Chronic high blood sugar triggers inflammation, oxidative stress, and the buildup of harmful sugar-protein compounds in retinal tissue. These processes damage the nerve cells at the back of the eye that transmit visual signals to the brain. Studies of retinal tissue from people with diabetes show elevated markers of cell death in these nerve cells. Beyond nerve damage, diabetes also raises the fluid pressure inside the eye, which is the most well-known risk factor for glaucoma.

The longer you’ve lived with diabetes, the higher your cumulative risk of developing glaucoma. It is worth noting that Medicare covers the cost of glaucoma screening for individuals at high risk for glaucoma. High risk Medicare beneficiaries include those who have diabetes.

There is a second type of glaucoma, neovascular glaucoma, that diabetes can directly cause. Neovascular glaucoma is less common but more aggressive than open-angle glaucoma. It occurs when advanced diabetic retinopathy causes the growth of new and abnormal blood vessels on the iris (colored part of the eye) and in the eye’s drainage system. The new vessels can block the flow of fluid out of the eye, which can cause the eye pressure to spike rapidly. Unlike open-angle glaucoma, which develops slowly and painlessly over years, neovascular glaucoma can cause sudden pain, redness, and vision loss.

The connection between diabetes and glaucoma isn’t just about whether you develop it. How well you manage your blood sugar levels also affects how quickly glaucoma worsens once it’s present. There isn’t a way to prevent glaucoma, but treatment can help stop it from getting worse. That’s why catching glaucoma early is so important. Regular dilated eye exams are critical for anyone with diabetes.