Diabetic retinopathy is a complication of diabetes caused by uncontrolled blood sugar levels damaging the blood vessels and eye tissue located at the retina. The condition occurs in patients with both type 1 and type 2 diabetes and is the leading cause of blindness among adults of working age. 

About 1 in 3 people with diabetes, or 9.6 million Americans, will be diagnosed with the condition, which can cause floaters, blurred vision, dark empty areas in the field of vision, and full vision loss.

But primary care physicians can play an important role in helping patients avoid diabetic retinopathy through better control of blood sugar, blood pressure, and cholesterol, as well as regular eye exams. Additionally, a wide variety of treatments can slow the progression of the disease and reduce loss of eyesight, especially when the condition is caught early.

How to Prevent Diabetic Retinopathy in At-Risk Patients

Excessive glucose in the bloodstream can cause the walls of blood vessels around the retina to weaken. It can also cause damaged blood vessels to close up or, in some cases, leak into the center of the eye. But in all cases, well-controlled blood sugar is one of the most important tools for prevention.

“The longer a person has diabetes and the longer their blood sugar is uncontrolled, the greater the risk,” said Neil M. Bressler, MD, an ophthalmologist who specializes in retina and vitreous diseases at Johns Hopkins University in Baltimore.

Primary care physicians can help patients manage their blood sugar through regular checkups every 3 to 6 months, especially in those who are having trouble keeping their blood sugar and A1c levels in check.

Patients should limit refined sugars, processed foods, alcohol, and sugary drinks and get at least 150 minutes of moderate exercise per week. Smoking is also a risk factor because it increases blood sugar. Additionally, a genetic predisposition also increases the risk for the eye disease, though experts don’t fully understand this connection.

Primary care physicians can also prescribe insulin management medications, such as metformin, and insulin therapy while discussing the importance of vigilant patient glucose monitoring using a glucose meter and finger stick or a continuous glucose monitor. 

Physicians should also monitor cholesterol, another risk factor that leads to chronic inflammation as well as a complication called diabetic macular edema, which occurs when fluid leaks into the macula and damages the center of the retina. 

Beyond blood sugar and cholesterol, Bressler said that changes in blood pressure are also a risk factor for diabetic retinopathy because it puts additional stress on the walls of retinal capillaries, further damaging blood vessels.

A study published in the journal Cell found that a blood pressure reading over 120/80 mm Hg significantly increased the prevalence of diabetic retinopathy by 10%-20% in diabetes patients with or without hypertension.

“Blood pressure should be controlled as best as possible, and doctors should notice changes,” said Bressler.

Primary care physicians should also be sending patients to an ophthalmologist to check their vision, especially if they’re noticing any potential changes. These tests include a basic vision acuity test, tonometry to test for eye pressure and glaucoma, and optical coherence tomography, which uses light waves to take images of the retina, said Bressler. Patients with diabetes may also require a dilated eye exam at least once per year.

Additionally, patients with type 1 and type 2 diabetes prior to pregnancy are also at an increased risk for the condition. Research has shown that it can accelerate risk, especially in the second trimester of pregnancy. These patients should be monitored by their primary care physician or obstetrician to ensure their vision isn’t impacted.

The Impact of GLP-1s on Diabetic Retinopathy

While long-term use of GLP-1 agonists may improve vision outcomes for patients with diabetes, research has shown that this is not true in the short term.

“In people who have diabetes, when they’re on GLP-1s, they experience an early increase in the risk of diabetic retinopathy,” said Ziyad Al-Aly, a clinical epidemiologist at Washington University in St. Louis and an expert in GLP-1s.

While experts aren’t completely sure why these obesity medications increase a patient’s risk for the condition, a number of factors could be at play. Patients who were included in the study may have already had some form of preexisting diabetic retinopathy, for example. 

What’s more, while high blood sugar levels may cause the condition, a rapid decrease in blood sugar may leave too little glucose to feed the eye tissue, which can lead to an increased incidence of the condition, said Al-Aly.

A study published in the January 2025 issue of the journal JAMA Open Network found that patients with type 2 diabetes treated with GLP-1 receptor agonists should be regularly screened and monitored for potential complications such as vision changes.

Primary care physicians should talk to their patients about weighing the pros and cons and potentially considering a reduction in the dose of their GLP-1 medication so that blood sugar is reduced, but not in such a rapid fashion, said Al-Aly.

Treatments for Patients With Diabetic Retinopathy

If diabetic retinopathy is detected, physicians are much better equipped to slow or stop disease progression and preserve vision in the long term, said Sandip Suresh, MD, an ophthalmologist at CLS Health in Houston.

Treatments are geared toward reducing damage in the blood vessels to stave off further damage. Laser therapy, called photocoagulation, seals off leaking vessels or shrinks abnormal blood vessels, and anti-VEGF can be injected directly into the eye to reduce leaky blood vessels and retinal swelling, thus reducing the abnormal production of blood vessels that can grow in the eye.

Additionally, corticosteroid injections or implants can help control retinal swelling. Vitrectomy surgery, which is recommended for advanced cases, removes blood and scar tissue from the eye to restore or preserve vision.

In the end, it’s about reducing damage to the delicate eye tissue and vessels around the retina so that loss of vision doesn’t become a long-term complication of an already complex disease. And with thoughtful prevention, screening, and treatments, patients don’t have to fear losing their eyesight.

“Early detection through routine screenings combined with good diabetes management significantly reduces the risk of vision loss from diabetic retinopathy,” said Suresh.