Diabetes and Your Eyes: How High Blood Sugar Can Affect Your Vision
When people think about diabetes, they usually think about blood sugar.
But diabetes can affect much more than glucose levels.
Over time, persistently high blood sugar can damage blood vessels throughout the body — including the tiny blood vessels inside the eyes.
This can lead to a condition called diabetic retinopathy, which can threaten eyesight if it is not detected and managed.
During World Retina Week from 22–28 September and Eye Care Awareness Month, it is worth understanding why regular eye checks are an important part of diabetes care.
What is the retina?
The retina is a thin layer of light-sensitive tissue at the back of your eye.
It receives light and converts it into signals that are sent to the brain, allowing you to see.
Because the retina depends on a network of very small blood vessels, conditions that damage blood vessels — including diabetes — can affect how well it functions.
What is diabetic retinopathy?
Diabetic retinopathy occurs when high blood sugar damages blood vessels in the retina.
Over time, these vessels can become blocked, weakened or leaky.
As the condition progresses, abnormal new blood vessels may also develop.
These vessels are fragile and can bleed inside the eye.
Diabetic retinopathy is one of the recognised causes of vision impairment and blindness worldwide.
The dangerous part: you may have no symptoms
One of the most important things to know about diabetic retinopathy is that the early stages often cause no noticeable symptoms at all.
Your vision may appear completely normal while changes are developing inside the eye.
That means waiting until you notice a problem is not a reliable way to protect your eyesight.
This is why people living with diabetes need regular eye examinations even when they can see perfectly well.
What symptoms can appear later?
As diabetic eye disease progresses, symptoms may include:
- Blurred vision
- Difficulty reading
- Difficulty seeing objects clearly at a distance
- Dark or floating spots
- Lines or cobweb-like shapes in your vision
- Areas of vision that appear dark or empty
- Vision that seems to change from day to day
- Progressive loss of eyesight
The National Eye Institute notes that floating spots or streaks can appear when damaged retinal blood vessels bleed into the gel-like substance inside the eye.
Any new or persistent vision change should be assessed.
Why does high blood sugar damage the eyes?
Blood vessels throughout the body are sensitive to prolonged high glucose levels.
Inside the retina, elevated blood glucose can damage these small vessels.
They may begin leaking fluid or blood, or become blocked entirely.
The eye may then attempt to compensate by growing new blood vessels.
Unfortunately, these new vessels tend to be fragile and may leak or bleed easily.
This process can eventually damage the retina and affect vision.
Diabetes can cause more than retinopathy
Diabetic retinopathy is not the only eye condition associated with diabetes.
People living with diabetes also have an increased risk of other problems, including:
- Cataracts
- Glaucoma
- Diabetic macular oedema
The macula is the part of the retina responsible for sharp central vision.
When damaged retinal vessels leak fluid into this area, swelling can develop and vision may become blurred.
How long you have had diabetes matters
Anyone with diabetes can develop diabetic retinopathy.
This includes people with:
- Type 1 diabetes
- Type 2 diabetes
- Diabetes during pregnancy
The risk generally increases the longer someone has been living with diabetes.
However, this does not mean vision problems are inevitable.
Managing diabetes carefully and attending recommended eye examinations can substantially reduce the risk of serious complications.
Blood pressure matters too
Blood sugar is only part of the picture.
High blood pressure can place additional strain on blood vessels, including those in the eye.
High cholesterol can also contribute to vascular damage.
If you live with diabetes, protecting your eyesight therefore means paying attention to:
- Blood sugar
- Blood pressure
- Cholesterol
- Smoking
- Overall cardiovascular health
The National Eye Institute specifically notes that controlling blood pressure and cholesterol can help reduce the risk of vision loss in people with diabetic retinopathy.
Regular eye examinations are essential
A normal vision test alone does not always tell the full story.
A healthcare professional examining the inside of your eye can detect changes in the retina before you are aware of them.
A dilated eye examination involves using drops to widen the pupil so that the structures at the back of the eye can be examined more thoroughly.
The National Eye Institute recommends that most people with diabetes receive a comprehensive dilated eye examination at least once a year, although some people may need more frequent monitoring depending on their individual risk and findings.
Your own healthcare provider or eye-care professional can advise how frequently you should be checked.
Pregnancy and diabetes need extra attention
Pregnancy can sometimes cause diabetic retinopathy to develop or progress more quickly in women who already have diabetes.
If you have diabetes and become pregnant, tell the healthcare professionals managing your pregnancy and diabetes.
The National Eye Institute recommends an eye examination early in pregnancy for women with pre-existing diabetes, with additional follow-up when necessary.
Can diabetic retinopathy be treated?
Yes.
Treatment depends on how advanced the disease has become.
Options can include:
- Medication injected into the eye
- Laser treatment
- Surgery in more advanced cases
Treatment cannot always restore vision that has already been permanently lost.
That is why early detection matters so much.
Finding diabetic retinopathy before significant damage develops gives healthcare professionals a better opportunity to protect remaining vision.
Managing diabetes helps protect your eyesight
Good diabetes management remains one of the most important ways to reduce your risk.
This includes:
- Taking diabetes medication as prescribed
- Checking blood glucose when advised
- Attending routine medical appointments
- Eating a balanced diet
- Staying physically active
- Managing blood pressure
- Managing cholesterol
- Avoiding smoking
WHO notes that diabetes can cause permanent vision loss by damaging blood vessels in the eyes, but regular screening and appropriate treatment can help prevent or delay complications.
Don’t stop medication because you feel well
Type 2 diabetes can cause very mild symptoms — or no obvious symptoms for a long time.
The same is true of some of its complications.
If your blood sugar improves while using medication, that does not necessarily mean you no longer need treatment.
It may mean the treatment is working.
Do not stop diabetes, blood-pressure or cholesterol medication without discussing it with the healthcare professional managing your condition.
When are eye symptoms urgent?
Some vision changes need prompt medical assessment.
Seek urgent care if you experience:
- Sudden loss of vision
- A sudden large increase in floaters
- New flashes of light
- A dark curtain or shadow across your vision
- Sudden significant blurring
- Severe eye pain
- Vision loss following an eye injury
These symptoms may be related to conditions other than diabetic retinopathy, but they should not be ignored.
You don’t have to wait until your eyesight changes
Diabetic eye disease is a good example of why preventative healthcare matters.
By the time some people notice that their eyesight is changing, significant damage may already have occurred.
Regular eye examinations allow changes to be identified sooner.
WHO estimates that at least 2.2 billion people globally live with near or distance vision impairment, and at least 1 billion cases could have been prevented or remain unaddressed.
Protecting vision therefore starts long before eyesight is lost.
Speak to a TruMD Eswatini healthcare professional
If you live with diabetes and are concerned about your blood sugar, blood pressure, medication or changes in your vision, TruMD Eswatini gives you convenient access to qualified healthcare professionals.
You can discuss your diabetes management and whether further blood tests, eye screening or an in-person assessment may be necessary.
An online consultation cannot replace a detailed examination of the retina, so where an eye examination is required, your healthcare professional can advise you on the appropriate next step.
If you have diabetes, looking after your eyesight starts before you notice a problem.
Keep your blood sugar under control, know your blood pressure and make regular eye checks part of your diabetes care.
