Why does hyperglycemia cause blurred vision?

Understanding Hyperglycemia and Blurred Vision

Hyperglycemia refers to a condition where blood sugar levels become abnormally high. It is a common condition in people living with diabetes. Among the many symptoms associated with hyperglycemia, blurred vision stands out as a persistent issue that can significantly reduce an individual’s quality of life.

If you’ve ever wondered why hyperglycemia causes blurred vision, this article will explore some of the key factors involved.

What Causes Hyperglycemia?

One of the primary causes of hyperglycemia is insulin resistance. In other words, the body is producing insulin, but it is not being used efficiently. Alternatively, the body may not produce enough insulin, leading to a buildup of glucose in the blood. Other factors that can contribute to hyperglycemia include stress, medication, infection, and lack of exercise.

Why Does Hyperglycemia Cause Blurred Vision?

Hyperglycemia can cause a range of eye problems, including blurry vision, double vision, and even blindness. One of the ways this happens is through changes to the shape of the eye’s lens. This occurs due to the buildup of glucose in the aqueous humor, a fluid that provides nourishment to the eye. As glucose levels increase, the fluid becomes more viscous, changing the shape of the lens and leading to blurred vision.

In addition to changes to the lens, hyperglycemia can also damage the blood vessels supplying oxygen and nutrients to the eye. This damage can lead to a condition called diabetic retinopathy, where the blood vessels leak or become blocked, causing vision loss and, in severe cases, blindness.

How Does Diabetic Retinopathy Develop?

Diabetic retinopathy often develops in people with poorly controlled diabetes. It occurs due to damage to the small blood vessels in the retina, a thin layer of tissue at the back of the eye. Increased glucose levels cause blood vessels to weaken and become more permeable, allowing fluid to leak into the retina, resulting in swelling and failure of the delicate blood vessels.

The changes that occur in the retina can range from mild to severe. In the early stages, blood vessels may leak fluid into the retina, leading to swelling and reduced vision. In advanced cases, new blood vessels may grow in the retina, which can lead to bleeding and scarring. This can cause the retina to detach from the back of the eye, impairing vision or causing blindness.

Other Factors That Contribute to Blurred Vision in Diabetes

While hyperglycemia is a significant factor in blurred vision in people with diabetes, other factors can also cause vision problems. Some of these factors include:

  • Cataracts – a clouding of the eye’s lens
  • Glaucoma – Damage to the optic nerve leading to vision loss
  • Dry Eye – a condition where the eye doesn’t produce enough tears or is unable to maintain an adequate tear film

It is essential to discuss any vision problems with your doctor, who can help determine the cause and recommend appropriate treatment.

Treatment of Blurred Vision Caused by Hyperglycemia

The best way to treat blurred vision caused by hyperglycemia is to get blood glucose levels under control. Often, once glucose levels are brought back to normal, the changes to the lens reverse, and vision improves. Diabetic retinopathy can also be treated by controlling blood sugar levels, blood pressure, and cholesterol levels. Treatments may also include laser surgery, injections of medications into the eye, and surgical removal of blood to resolve macular edema.

Prevention is Key!

The best way to avoid vision problems associated with hyperglycemia is to keep blood sugar levels in check. This includes following a healthy diet, engaging in regular physical activity, and taking any medications as prescribed. You should also get regular eye exams to detect any changes to your vision early.


Hyperglycemia is a common condition among individuals living with diabetes, and blurred vision is one of the most characteristic symptoms associated with this disease. Through this article, we have explored some of the reasons why hyperglycemia causes blurred vision, including changes to the shape of the eye’s lens and damage to the blood vessels supplying the eye. It is essential to get the condition under control as soon as possible and to obtain regular eye exams to detect any vision changes early.


  • American Diabetes Association. (2021). Hyperglycemia (High Blood Glucose). Retrieved from https://www.diabetes.org/diabetes/medication-management/blood-glucose-testing-and-control/hyperglycemia
  • National Eye Institute. (2020). Diabetic Eye Disease. Retrieved from https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/diabetic-eye-disease
  • Strategic Planning Task Force of the International Diabetes Federation. (2011). IDF Diabetes Atlas. 5th ed. International Diabetes Federation. ISBN 9782930229850.