Causes and Risk Factors of Diabetic Retinopathy

Diabetic retinopathy involves the eye's blood vessels and retinal tissue. It is the most common cause of vision loss for those with diabetes mellitus, which is a chronic condition of high blood sugar that includes both type 1 diabetes and type 2 diabetes.

The eye's blood vessels and the light-sensitive retinal tissue at the back of the eye are affected by high blood sugar. High blood sugar can damage blood vessels and cause them to leak. If the fluid leaks into the retina, it can cause swelling.

Diabetic retinopathy can also cause abnormal new blood vessels to form on the retinal surface, called neovascularization.

This article will highlight the causes, genetic links, risk factors, and more to help you understand how diabetic retinopathy affects vision and your vulnerabilities to developing this condition.

Person being given an eye examination by an eye doctor

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Common Causes

Diabetic retinopathy is linked to high blood sugar, which puts anyone with diabetes, a condition in which your body doesn't metabolize glucose as it should, at risk.

Sugar can cause a blockage in the blood vessels and cause damage to them anywhere in the body. In the eye, leaky blood vessels can harm the retina. Your retina is key in sensing light and conveying that information to the brain via the optic nerve.

The body attempts to grow new blood vessels to compensate for damaged blood vessels. Unfortunately, these too can leak and bleed, which can lead to retinal damage.

Other health factors that can increase the likelihood that diabetes may result in a case of diabetic retinopathy include:

Genetics

It can be unclear why one person with diabetes develops diabetic retinopathy and another does not. Even if your only known predisposing factor is diabetes, your genes can also play a role in the odds that you may develop a case of diabetic retinopathy.

Genes can potentially affect everything from the initial incidence of diabetic retinopathy to its progression. The heritability of diabetic retinopathy due to genes linked to it is estimated to be 27%, and for some more severe types, it is 52%.

Heritability is a statistic used in genetics to say how much an observable trait (like diabetic retinopathy) is due to genetic variation between people. Lower heritability means that it more likely develops due to factors other than genes. Higher heritability means it is more likely to occur due to genes than to other factors.

Some genes that are being studied and that may play a role include the following:

  • AKR1B1
  • VEGFA
  • AGER
  • EPO
  • NOS3

This list continues to grow, with others also potentially in the mix.

Cardiovascular

Cardiovascular risk factors can contribute to the development of diabetic retinopathy. These cardiovascular factors include:

  • High lipid levels: Some of the materials that leak from damaged blood vessels into the retina in cases of diabetic retinopathy are lipids (fats). Those with high lipid levels and type 2 diabetes that develops later in life may be at heightened risk of developing diabetic retinopathy.
  • Elevated serum cholesterol: Some trials have linked high serum cholesterol (part lipid, part protein) to diabetic retinopathy-related vision loss. In one study, those with a cholesterol level of 244 milligrams per deciliter (mg/dL) were more likely to develop severe vision loss than those with cholesterol levels of 228 or lower.
  • High blood pressure: People with increased systolic (the arterial pressure as your heart beats) blood pressure and type 2 diabetes are at greater risk of developing diabetic retinopathy. This likely is due to increased blood flow putting pressure on damaged blood vessels for those with diabetes.

Lifestyle Risk Factors

Lifestyle-associated risks can contribute to the likelihood that you will develop diabetic retinopathy. Unlike genetic risks, you can change these. Modifications you can make include:

  • Avoid or quit smoking since smoking can raise blood sugar levels.
  • Lower your blood sugar levels.
  • Eat healthy foods low in sugar, salt, and fat
  • Maintain or get to a healthy weight, which means having a body mass index (BMI) in the range of 18.5 to 24.9.
  • Limit alcohol to no more than one glass of wine or one can of beer per day.
  • Increase activity, such as by walking or cycling a minimum of around 20 minutes a day and walking around 10,000 steps each day.

Summary

People with diabetes are vulnerable to developing diabetic retinopathy, which affects the blood vessels of the eyes. Sugar in the blood can block these blood vessels, damaging them and causing them to leak and potentially damage the retina.

Risk factors for developing diabetic retinopathy range from high blood sugar levels and length of time you've had diabetes to your genetic make-up and cardiovascular issues, as well as your individual lifestyle.

A Word From Verywell

Not everyone who has diabetes will develop diabetic retinopathy. The more you know about the causes and risk factors, the more apt you are to be able to avoid this complication or to turn this around before the damage becomes severe and affects your vision.

Frequently Asked Questions

  • Can diabetic retinopathy cause blindness?

    Yes. If sugar levels are not controlled, this is a real risk. It can take several years before damage to blood vessels associated with diabetic retinopathy reaches the point where sight is lost. It's important that diabetic retinopathy be diagnosed and treated to help avoid this possibility.

  • What are the risk factors for diabetic retinopathy?

    The longer you have diabetes and the higher your blood sugar levels are, the more likely you are to develop diabetic retinopathy. Also, if you have high blood pressure, are pregnant, or smoke, you are at increased risk of developing this condition.

  • Can diabetic retinopathy be reversed?

    While vision loss from diabetic retinopathy cannot be reversed once the damage is done, the condition itself can be slowed down and reversed by what's known as anti–vascular endothelial growth factor therapy (anti-VEGF medication), which reduces new blood vessel growth.
    It can also be helpful to bring your blood sugar levels down, lower your blood pressure, and reduce your cholesterol levels.

  • What is the first sign of diabetic retinopathy?

    Unfortunately, there often are no initial signs of diabetic retinopathy. But there are some who do find they have trouble reading or seeing at a distance from time to time.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Maxine Lipner
Maxine Lipner is a long-time health and medical writer with over 30 years of experience covering ophthalmology, oncology, and general health and wellness.