Healthdirect Free Australian health advice you can count on.

Medical problem? Call 1800 022 222. If you need urgent medical help, call triple zero immediately

healthdirect Australia is a free service where you can talk to a nurse or doctor who can help you know what to do.

beginning of content

Blood glucose test

2-minute read

Blood glucose tests are also sometimes called blood sugar tests. They can be done after you have fasted or as a test called an oral glucose tolerance test. They are usually used to check for or monitor diabetes.

What is being tested?

This test measures the amount of glucose in your blood. Glucose is a simple sugar that provides energy for the body.

People with diabetes often monitor their own blood glucose at home. This is done using a finger-prick test and a special machine, rather than a blood sample taken from a vein.

You might have blood taken for a blood sugar level. You might or might not be asked to fast beforehand.

There is also a test called an oral glucose tolerance test, abbreviated as OGTT or GTT. For this test you fast, then have a blood sample taken, then drink glucose, then have a number of samples taken over a few hours.

Why would I need this test?

You might need this test if you are at risk of developing diabetes, or if you have had any symptoms or test results suggesting diabetes.

The standard blood glucose tests measure your blood sugar level at a particular time. The OGTT measures how you respond to glucose.

Pregnant women can develop a particular type of diabetes called gestational diabetes, and will be asked to have an OGTT around 24 to 28 weeks of pregnancy. Gestational diabetes usually goes away after the baby is born.

ARE YOU AT RISK? — Are you at risk of type 2 diabetes, heart disease or kidney disease? Use our Risk Checker to find out.

How to prepare for this test

If you’re asked to fast, you can’t eat anything for 8 to 10 hours before the test. You should drink only water.

If you are having an OGTT, you will need to adjust your diet for a few days before the test and fast for 8 hours just before the test.

Understanding your results

High levels of glucose can indicate diabetes or being at risk of diabetes. There are other conditions that can also cause high glucose levels. You will need to discuss with your doctor what the test results mean for you, given your specific circumstances.

More information

About blood glucose testing

Visit PathologyTests Explained website for more information about blood glucose testing.

About blood testing

Visit our ‘Guide to blood testing’ to learn more about blood tests in general with information such as:

  • what to consider before having the test
  • what happens during a blood test
  • results accuracy
  • blood tests cost

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: June 2020


Back To Top

Need more information?

These trusted information partners have more on this topic.

Top results

Blood glucose testing - MyDr.com.au

Blood glucose testing measures the amount of glucose (sugar) in your blood, and is one of the most common screening tests used for diabetes.

Read more on myDr website

Type 1 diabetes blood glucose monitoring | Diabetes NSW & ACT

Understand why blood glucose monitoring is important to your health and how it helps to ensure your blood glucose levels stay in the target range. Read more

Read more on Diabetes NSW and ACT website

Glucose - Pathology Tests Explained

Describes how the blood glucose test is used, when the glucose test is requested, and what the results of tests might mean.

Read more on Pathology Tests Explained website

Managing your diabetes - Diabetes Australia

Learn more about how to manage:

Read more on Diabetes Australia website

Continuous glucose monitoring - Diabetes Australia

Continuous Glucose Monitoring (CGM) is a means of measuring glucose levels continuously in order to gain insight into patterns and trends in glucose levels

Read more on Diabetes Australia website

HbA1c test results and diabetes - MyDr.com.au

The HbA1c (glycated haemoglobin) test is a useful, simple and inexpensive blood test that can be used to diagnose diabetes and also to monitor blood glucose control in people with known diabetes.

Read more on myDr website

Why HbA1c testing? What’s it all about? | Diabetes NSW & ACT

The HbA1c test is a way of looking at your average blood glucose level over a period of time. We explain why its useful in helping to manage your diabetes

Read more on Diabetes NSW and ACT website

Diabetes - Pathology Tests Explained

Diabetes is a common condition affecting individuals with abnormally high levels of blood sugar.

Read more on Pathology Tests Explained website

Diabetes type 1 - Better Health Channel

betterhealth.vic.gov.au

Read more on Better Health Channel website

Type 1 diabetes - MyDr.com.au

Type 1 diabetes is a condition where the pancreas doesn't make enough insulin, resulting in high blood glucose (sugar) levels.

Read more on myDr website

Healthdirect 24hr 7 days a week hotline

24 hour health advice you can count on

1800 022 222

Government Accredited with over 140 information partners

We are a government-funded service, providing quality, approved health information and advice

Australian Government, health department logo ACT Government logo New South Wales government, health department logo Northen Territory Government logo Government of South Australia, health department logo Tasmanian government logo Victorian government logo Government of Western Australia, health department logo

Healthdirect Australia acknowledges the Traditional Owners of Country throughout Australia and their continuing connection to land, sea and community. We pay our respects to the Traditional Owners and to Elders both past and present.