Pre-diabetes can impact the health of your eyes. High blood glucose levels can damage the blood vessels at the back of the eyes, a process that can start at pre-diabetes and early diagnosis of diabetes. In this article we’ll look at how pre-diabetes affects vision as well as how pre-diabetes and pre-diabetes-related vision problems can be prevented.

What is pre-diabetes?

Pre-diabetes is a condition where blood glucose levels are higher than normal but not high enough to be diagnosed as type 2 diabetes. Having pre-diabetes increases the risk of developing type 2 diabetes by between 10 and 20 times. However, this can be prevented or delayed.

How does pre-diabetes develop?

When we eat or drink, glucose (sugar) enters the bloodstream and the hormone insulin is released by the pancreas so that glucose can be used by the muscles for energy or fuel. Pre-diabetes develops when the body cannot do this effectively. 

Who’s at risk of pre-diabetes?

The exact cause of pre-diabetes is unknown, but the risk factors are similar to those for type 2 diabetes. They can be split into two groups: 

  1. modifiable (meaning that they can be changed)
  2. non-modifiable (meaning that they can’t be changed).

Modifiable risk factors include your weight, your diet and the amount of exercise you do. Non-modifiable risk factors include your age, ethnicity and your family medical history. A more detailed list can be found here.

According to Diabetes Australia, two million Australians have pre-diabetes.

Understanding pre-diabetes: the link between blood glucose and vision health

High blood glucose levels can damage the blood vessels at the back of the eyes, a process that can start at pre-diabetes and early diabetes. This may allow fluid to leak from the vessels and cause swelling. Alternatively, the blood vessels may bleed directly into the eye, causing high pressure or scarring. High blood glucose can also alter eye tissue, temporarily blurring vision. 

To avoid serious problems with your vision, it’s very important to manage your blood glucose levels.

Vision problems that are commonly associated with pre-diabetes

Diabetic retinopathy
Retinopathy is damage to the retina, the part of the eye that converts light into signals that the brain interprets as vision. Diabetic retinopathy occurs when high blood glucose levels weaken the capillaries (small blood vessels) in the retina, causing abnormal blood vessels to form. These may bleed or leak fluid. Over time, this can result in scar tissue and blindness. Research has shown that nearly 8% of people develop diabetic retinopathy during the pre-diabetic stage.

Diabetic macular oedema (DMO)
This is a complication of diabetic retinopathy. It occurs when fluid builds up on the retina and causes swelling of the macula, the part of the retina that handles detailed vision. This results in blurry vision.

Diabetic cataracts
High blood glucose levels can increase the risk of developing cataracts, which affect the eye’s lens, causing clouded vision.

People with high blood glucose levels have twice the risk of developing glaucoma, a word for a group of eye diseases that can damage the optic nerve and result in blindness. 

Blurred vision can be a symptom of pre-diabetes and diabetes. If you notice your vision changing, it is important to get your blood glucose levels tested.

Detecting pre-diabetes: early warning signs and symptoms for vision problems

Pre-diabetes often has no warning signs or symptoms. However, high blood glucose levels can lead to pre-diabetes, and its symptoms include:

  • increased thirst and frequent urination
  • unplanned weight loss
  • blurry vision
  • infections.

If you experience any of the above, you should see your doctor. If you are subsequently diagnosed with pre-diabetes, you can take steps to prevent or delay its progression to type 2 diabetes, a condition that can increase the risk of complications like heart and kidney diseases.

Lifestyle changes to maintain healthy vision

If you have the non-modifiable risk factors mentioned above, you can prevent pre-diabetes and reduce the risk of retinopathy by living a healthier lifestyle. It’s important to focus on: 

  • maintaining a healthy weight
  • eating healthy and nutritious food
  • reducing alcohol to two standard drinks per day
  • Managing blood pressure levels
  • doing regular moderate exercise.

Diagnosis and tests

Pre-diabetes is diagnosed by the following blood tests.

Fasting glucose test (FGT)
The test for high blood glucose levels or diabetes is called a fasting glucose test (FGT). A blood sample is taken to show the level of glucose in your blood after fasting (not eating or drinking anything other than water) for 8–10 hours. 

Oral glucose tolerance test (OGTT)
If the results show that you have  pre-diabetes, your doctor will ask you to have an oral glucose tolerance test (OGTT). Again, a blood sample is taken to check the level of glucose in your blood after fasting. You then have a glucose drink and another blood sample is taken. 

HbA1c test
Your doctor may also ask you to take an HbA1c test. This checks your average blood glucose level over the past three months.

When to see a doctor

How do doctors diagnose eye problems from diabetes?

Eye problems caused by diabetes are usually diagnosed through a diabetes eye test. This is why it’s a good idea to have a full check-up with an optometrist at least once a year if you have diabetes. The check-up will include a dilated eye exam where drops are placed in your eyes to widen your pupils, allowing the ophthalmologist to examine the back of each eye.

If you are diagnosed with eye disease, your doctor will suggest ways of managing your diabetes to prevent your eyes getting worse. Medication to prevent the growth of abnormal blood vessels in the eye and stopping fluid leaks can also be useful.

Some cases of diabetic eye disease may require a review by a specialist doctor, an ophthalmologist.

If you notice sudden changes to your vision such as flashing lights or spots before your eyes, you should see a doctor or optometrist as soon as possible.


Understanding the connection between pre-diabetes and the health of your eyes is crucial.

It’s also important to be aware that prediabetes-related vision problems can be treated—or even prevented.

The evidence shows that type 2 diabetes can be prevented or delayed in up to 58% of cases of pre-diabetes.  If you’ve been diagnosed with pre-diabetes, there are many positive steps you can take. It’s important to act quickly—the sooner you start, the sooner your risk level will decrease.

But it’s not easy making lifestyle changes on your own. Most of us know that we have to exercise more and prioritise a healthy diet and weight loss, but it’s easier said than done. A great way to achieve this is to join a healthy lifestyle program and to have the support of health professionals.

This is where the Life! program can help. 

Life! is a free healthy lifestyle program that helps you improve your eating habits, increase your physical activity and manage stress. You can choose from a group course or our telephone health coaching service.

The Life! program will support you to reduce the risk of your pre-diabetes progressing to type 2 diabetes.

Life! is run by experienced health professionals, including dietitians and exercise physiologists, who guide and support you to make realistic healthy lifestyle changes that suit your needs. The program includes 7 sessions delivered over a 12-month period.

Since 2007, over 75,000 Victorians have learnt more about living a healthy life with the Life! program. It is the largest prevention program of its kind in Australia.

Find out more about the program and check your eligibility for joining with this simple online health test.


Pre-diabetes – Diabetes Australia

Insulin and Insulin Resistance: The Ultimate Guide – Healthline

Prediabetes – Mayo Clinic

Prediabetes and Dangers to Your Eyesight by Dhanu Meleth, M.D. – Marietta Eye Clinic

Prediabetes And Your Vision: Know The Facts – VisionSource

What You Need to Know About Type 2 Diabetes – Healthline

5 Ways Diabetes Can Affect Your Eyes & Vision – WebMD

Diabetes and Your Eyes: What You Need to Know – JHM

Diabetic Eye Disease – NIDDK – National Institute of Diabetes and Digestive and Kidney Diseases

Diabetic retinopathy – Mayo Clinic

Diabetic retinopathy – Prevention – NHS

Insulin Resistance and Diabetes – Centers for Disease Control and Prevention

Insulin Resistance: What It Is, Causes, Symptoms & Treatment – Cleveland Clinic

Insulin Resistance: What It Is, Causes, Symptoms & Treatment – Cleveland Clinic

Is Diabetes Genetic? Hereditary Risk Explained – GoodRx

Lifestyle and the Prevention of Type 2 Diabetes: A Status Report

Modelling the Interplay between Lifestyle Factors and Genetic Predisposition on Markers of Type 2 Diabetes Mellitus Risk – PloS one


Kristie Cocotis, Head of Prevention and Health Promotion

Sarah Dubé, Strategy and Engagement Lead

Ria Cheripuram, Digital Communications Officer

Tegan Kohlman, Communications and Social Marketing Officer

Iftu Umar, Program facilitator and Health Coach