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Summary

The HbA1c is a blood test used to diagnose type 2 diabetes and assess how well your glucose has been controlled over the previous few months. Even though you may have had some very high or very low blood glucose levels, HbA1c will give you a picture of the average amount of glucose in your blood over that period. The result can help you and your doctor know if the measures you are taking to control your diabetes are working.

Why get tested?

If your doctor suspects that you might have type 2 diabetes this test can help make a diagnosis. If diabetes is diagnosed, Diabetes Australia recommends that HbA1c is measured every three to six months. HbA1c is sometimes measured more often in people who have just been diagnosed with diabetes, if someone’s blood glucose remains too high, or if their treatment plan changes. 

 

Having the test

Sample
Blood


Any preparation?
None. The test does not require fasting and can be done at any time of day.

Your results

Reading your test report

Your results will be presented along with those of your other tests on the same result form.  You will see separate columns or lines for each of these tests. 
 

DIAGNOSISHbA1c RESULTCOMMENTS
NormalLess than 6.0 % (42 mmol/mol)Diabetes unlikely
DiabetesEqual to or more than 6.5% (48mmol/mol)Sometimes this test will need to be repeated to confirm the result
Prediabetes6.0 to 6.4 % (42 - 46 mmol/mol)These levels suggest a higher risk of developing diabetes

HbA1c is now usually reported with two sets of units. These are the % (NGSP) units that have been used for some time and the new Systeme International (SI) units which are mmol/mol, sometimes known as IFCC units. To convert results in % units to SI units the following equation may be used: HbA1c (mmol/mol) = 10.93 x HbA1c (% units) – 23.5

 

Treatment targets:

The general target is less than 7% (53 mmol/mol). If you have diabetes and your HbA1c is below the target of 7% (also reported as 53 mmol/mol) it is likely that your diabetes is under good control.

If your HbA1c rises above 7% (53 mmol/mol), you are at increased risk of developing long term complications such as eye disease, kidney disease or nerve damage and probably heart attack and stroke.

 

Conditions that can affect HBA1c results

Abnormal types of haemoglobin, for example if you suffer from sickle cell disease, can affect HbA1c levels. Accurate results can be obtained using an alternative method to measure your HbA1c.

Anaemia can cause low HbA1c levels because of excess breakdown of red blood cells (haemolysis) or heavy bleeding and test results may be falsely low.

Iron deficiency – a recent blood transfusion and erythropoietin therapy may affect your HbA1c measurements.

Pregnancy and chronic kidney disease can also affect the test result.


Reference intervals

Your results will be compared to reference intervals (sometimes called a normal range). 

  • Reference intervals are the range of results expected in healthy people. 
  • When compared against them your results may be flagged high or low if they sit outside this range.
  • Many reference intervals vary between labs so only those that are standardised or harmonised across most laboratories are given on this website.

If your results are flagged as high or low this does not necessarily mean that anything is wrong. It depends on your personal situation. Your results need to be interpreted by your doctor.
 

Questions to ask your doctor

The choice of tests your doctor makes will be based on your medical history and symptoms.   It is important that you tell them everything you think might help.

You play a central role in making sure your test results are accurate. Do everything you can to make sure the information you provide is correct and follow instructions closely.

Talk to your doctor about any medications you are taking. Find out if you need to fast or stop any particular foods or supplements. These may affect your results. Ask:

  • Why does this test need to be done?
  • Do I need to prepare (such as fast or avoid medications) for the sample collection?
  • Will an abnormal result mean I need further tests?
  • How could it change the course of my care?
  • What will happen next, after the test?
     

More information

Pathology and diagnostic imaging reports can be added to your My Health Record. You and your healthcare provider can now access your results whenever and wherever needed.

Get further trustworthy health information and advice from healthdirect.

Last Updated: Thursday, 1st June 2023

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