Reviewed by: HU Medical Review Board | Last reviewed: October 2020. | Last updated: March 2022
Type 2 diabetes can have both short- and long-term effects on the eyes. Blurred vision is 1 of the most common symptoms of poorly controlled blood glucose and can affect a person at any stage of diabetes. Both high and low levels of blood glucose levels can cause your vision to blur for periods of time.1
In type 2 diabetes, the body is resistant to insulin and eventually does not make enough insulin. This is a hormone that helps glucose, also known as sugar, get into cells so it can be used for energy. Because there is not enough insulin and the body is resistant to insulin to help this process, too much glucose stays in the blood.2
Vision problems are 1 of the most frightening complications of diabetes. The early symptoms of blurred vision caused by uncontrolled high blood glucose usually does not mean you are losing your eyesight. However, blurred vision means your blood glucose is not well controlled and that you need to take steps to prevent serious vision complications from occurring.
Why does diabetes cause blurred vision?
High blood sugar levels can cause the lens inside the eye to swell and change shape. This can make it hard for 1 or both of your eyes to focus, which makes your vision blurry for a short period of time. It can take about 6 weeks for the swelling to go away and your vision to return to normal once your blood sugar levels are closer to normal.1,2
Very low blood sugar levels can also cause blurred vision in 1 or both eyes. This is due to the way very low blood sugar levels affect the brain. Once your blood sugar levels have returned to normal, your vision should also return to normal.1,2
If your blood sugar levels often go up and down, you might notice that your vision gets better and then worse for different periods of time.1,2
What should I do if I experience blurred vision?
If you experience blurred vision and you have not been diagnosed with diabetes, you should see your doctor and discuss your symptoms. Your doctor will evaluate you and identify the cause of the symptom. As part of this evaluation, your doctor will measure your blood glucose to determine if it is high and whether you may have diabetes.
If you have already been diagnosed with diabetes, blurred vision is a sign that your blood glucose is out of control. You should work with your doctor on steps to help control your blood glucose.1,3
Do not get new glasses or contacts while you are working to get your blood glucose levels under control. Wait until after your levels are under control and the swelling in your eyes is gone so that your prescription is correct for your normal vision.1,3
No matter how often you experience blurred vision, you should always see your doctor since it could be a sign of another more serious eye problem.1,2
When high levels of blood sugar are left untreated for a long period of time, it can cause serious and sometimes permanent damage to 1 or both eyes. Long-term complications of diabetes that affect vision include:3
How can I protect my vision if I have diabetes?
Keeping your blood sugar levels under control and getting regular eye exams are the best things you can do to protect your vision.
Whether you have been living with type 2 diabetes for years or if you were recently diagnosed, your care team should include an ophthalmologist (eye specialist) who has experience providing eye care for people with diabetes. Your primary care doctor may be able to screen you in their office. If your results are abnormal, they can refer you to an ophthalmologist.1
It is important to have your eyes checked at least once a year, even if your vision has not changed. If you have diabetes, the key to protecting your eyes is catching complications early. When caught early, treatment for even some of the more serious vision complications of diabetes can be very effective.1
Have you experienced blurred vision?