What is an HbA1c test?

An HbA1c test is a blood test used to diagnose type 2 diabetes. It is also used to monitor blood sugar levels in people with type 1 and type 2 diabetes.

• HbA1c is glycated haemoglobin. It measures how much haemoglobin in your blood has glucose (sugar) attached to it.
• Haemoglobin (Hb) is a protein in red blood cells that carries oxygen throughout your body.
• A1c is the glucose attached to your haemoglobin.

Red blood cells live for about 120 days. An HbA1c test shows your average blood sugar level from the past 8 to 12 weeks. This is different from a standard blood glucose test, which measures your blood sugar level at a single point in time.

The test is also sometimes called haemoglobin A1c or glycated Hb.

When is a HbA1c test used?

Your doctor may suggest an HbA1c test if you are at risk of diabetes or have symptoms of diabetes.

If you have diabetes, the test shows how well your blood sugar has been controlled over the past 8 to 12 weeks. People with diabetes may be advised to have this test every 3 months. If your blood sugar levels are well-controlled, it may be done less often.

Monitoring HbA1c in people with diabetes is important. That's because the higher your HbA1c, the greater your risk of developing diabetes-related complications, such as:

• diabetic retinopathy (eye damage)
• diabetic nephropathy (kidney disease)
• diabetic neuropathy (nerve damage)

Where can I get the HbA1c test?

You usually need to go to a pathology collection centre with a referral from your doctor. Your doctor will recommend one near you.

Sometimes, your doctor will collect blood for testing in their clinic. Blood tests are also routinely done in hospitals.

How do I prepare for an HbA1c test?

There is no special preparation needed for an HbA1c test.

However, if you are having other blood tests done at the same time, you may need to prepare. Check with your doctor or the pathology collection centre if there is anything you need to do before your blood test.

What happens during an HbA1c test?

A health professional will take a sample of blood, usually from a vein in your arm. The blood will then be sent to a laboratory for testing.

What do my HbA1c test results mean?

It's important to discuss your test results with your doctor to see what they mean in your situation.

Diagnosis of diabetes

Diabetes may be diagnosed if your HbA1c result is 6.5% (48 mmol/mol) or higher. Your doctor may repeat the test to confirm the result.

If your HbA1c level is lower than this, you may need additional tests to check for diabetes or assess your risk. A lower result may also suggest prediabetes. This means your blood sugar is higher than normal but not high enough for a diabetes diagnosis.

Diabetes monitoring

If you have diabetes, the HbA1c target for most people is less than 6.5% (48 mmol/mol). However, your target may be different based on:

• the type of diabetes you have
• how long you have had diabetes
• your overall health

If your HbA1c result is higher than your target, your doctor may adjust your treatment or suggest closer monitoring of your blood sugar levels.

What can affect my result?

Some medical conditions can affect HbA1c accuracy, including:

• anaemia
• iron deficiency
• kidney failure
• pregnancy

Talk to your doctor about your results and what they mean for you.

Resources and support

Pathology Tests Explained provides information about HbA1c testing.

Read our 'Guide to blood testing' to learn more about blood tests, including:

• what to consider before having the test
• what happens during a blood test
• how accurate results are
• blood test costs

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available 24 hours a day, 7 days a week.