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Understanding your Blood Glucose Readings

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by

Philip Archer
in

How do you find out what your blood glucose level is?

There are two ways to track blood glucose levels: one is through a blood test taken by your GP or a pathology laboratory; the other is through monitoring yourself with a blood glucose meter. In this section we look at pathology blood glucose results, but for more information about self monitoring your blood glucose levels you can refer to our blood glucose monitoring fact sheet.
You may be asked to fast for a pathology blood glucose test or it could be taken without fasting. The diagnosis of diabetes or pre-diabetes, also known as Impaired Fasting Glucose (IFG) or Impaired Glucose Tolerance (IGT), must always be made on a laboratory blood glucose test. The laboratory test is based on a blood sample taken from the vein. A finger prick test is not adequate for the diagnosis of these conditions.

Did your blood glucose test require fasting?

Fasting results:
  • If your blood glucose result was less than 5.5mmol/L, diabetes is unlikely. It is recommended that you have your blood glucose retested in three years.
  • If your blood glucose result was between 5.5mmol/L – 6.9mmol/L, the result requires further investigation. It is recommended that you have an Oral Glucose Tolerance Test (OGTT).
  • If your blood glucose result was over 7.0mmol/L, another fasting test is required. If this test shows a blood glucose of 7.0mmol/L and over, then you have diabetes.
Or was your blood glucose test without fasting?
Random results:
  • If your blood glucose result was less than 5.5mmol/L, diabetes is unlikely. It is recommended that you have your blood glucose retested in three years.
  • If your blood glucose result was between 5.5mmol/L – 11.0mmol/L, an OGTT is required.
  • If your blood glucose result was 11.0mmol/L and over, a fasting blood glucose test is required.

Oral Glucose Tolerance Test (OGTT)

An OGTT is a fasting pathology test done to diagnose type 2 diabetes. First, a blood test is taken from a vein in your arm to check your fasting blood glucose level (BGL), and then you have a glucose drink. One hour after the drink, another blood glucose test may be taken; two hours after the drink, the last blood glucose test will be taken, again from your arm.
The Oral Glucose Tolerance Test could show:
a) diabetes is unlikely
b) definite diabetes, or
c) a condition called pre-diabetes (also known as IFG and IGT).
Both IFG and IGT are risk factors for type 2 diabetes so the test should be repeated in one year.