Blood glucose test

Blood glucose tests are used to help diagnose diabetes, and to monitor blood glucose and the effect of diet and medicines on your blood glucose levels. A blood glucose test measures the amount of glucose in the blood at the time of the test.

How is the test done?

The test may be either:

  • a 'fasting' blood glucose test — a fasting test is performed when you have not eaten anything for about 8 hours
  • a 'random' test — in a random or non-fasting test, blood samples may be taken at any time before or after a meal.

Note: The amount of glucose in the blood rises immediately after you eat, so waiting a few hours after eating before having the random test will give glucose levels a chance to drop back down and give more accurate results.

What does it tell me?

If the random or fasting blood glucose is high, then diabetes is likely. High glucose is indicated by the following test results:

  • fasting test: 7.0 millimoles [mmol] per litre [L] or higher
  • random test: 11.1 mmol/L or higher.

If the blood glucose test results are borderline, then the doctor will usually order an oral glucose tolerance test before a diagnosis of diabetes can be confirmed. A borderline blood glucose test result can indicate pre-diabetes. A borderline result would be:

  • fasting test: 5.5–6.8 mmol/L
  • random test: 5.5–11.0 mmol/L.

Related information - blood glucose test

Audience:
       

(Condition)
31 May 2016 Type 2 diabetes requires regular blood glucose monitoring. Find out more about self-monitoring to help you manage your diabetes.
(Medical test)
31 May 2016 Type 2 diabetes requires regular blood glucose monitoring. Find out more about tests and tools to help you manage your diabetes.
14 Mar 2016 How often should you monitor your blood glucose levels if you have type 2 diabetes? Download a factsheet about self-monitoring and managing diabetes.
For health professionals
01 Mar 2016 Find out which tests, treatments or procedures healthcare providers and consumers should question, as recommended by Australian medical colleges.
01 Mar 2016
Recommendations from the Endocrine Society of Australia on thyroid tests, testosterone therapy, insulin sensitivity tests & blood glucose self-monitoring.
01 Mar 2016
Recommendations from the Australian College of Nursing on peripheral IV catheters, blood glucose self-monitoring, antipyretics, urinary catheters & x-rays for ankle trauma.
22 Apr 2015
Recommendations from the Royal Australian College of General Practitioners (RACGP) on treating hypertension or hyperlipidaemia, prescribing benzodiazepines, self-monitoring of blood glucose, proton pump inhibitor therapy and screening for vascular disease.
(Topic)
02 Sep 2014 First-line investigations of fatigue should be targeted at picking up the relatively common diagnoses. Tests commonly ordered for fatigue are full blood count, thyroid function and serum ferritin.
(Medical test)
28 Jun 2013 Medical tests (usually blood tests) are used to help diagnose diabetes. Medical tests are also used to monitor blood glucose and the effect of diet and medicines on your blood glucose levels.
(Medical test)
08 Jan 2013 People with diabetes need to test their blood glucose regularly, by self-monitoring with glucose monitors at home & blood tests ordered by their doctor. Read about the different tests to help you monitor your diabetes.