HbA1c vs blood glucose testing: what does it all mean?

Friday, 13 October 2017

Along with your blood glucose levels that you have checked at home, your doctor may ask you to have regular HbA1c tests. What’s the difference between the two and what does it all mean?

Blood glucose levels

Checking your blood glucose levels at home can help you look after your diabetes.

They will  give you information to help with daily decisions around exercise, food and medication. Checking your blood glucose level at home tells you what is happening at that particular moment in time.

What is the HbA1c? Why is it so important?

The abbreviation HbA1c stands for ‘Glycosylated Haemoglobin’ and it’s a test that usually involves taking blood from your vein. There are some testing machines that can do your HbA1c from a finger prick but generally your doctor will refer you to a pathology service to have the test done.

The HbA1c reflects your average blood glucose level over the last 10-12 weeks and it is recommended that you have it done at least every 12 months, although you may be advised to have it done more often such as 3 to 6 monthly. A HbA1c test helps you see how well you are looking after your diabetes.

The HbA1c develops when haemoglobin, a protein within red blood cells that carries oxygen throughout your body, joins with glucose in the blood, becoming ‘glycated’. For people with diabetes this is important because the higher the HbA1c, the greater risk of developing diabetes related complications.

Red blood cells survive in your body for 8-12 weeks before they are renewed. This is the reason HbA1c tests are done at a minimum of 3 months apart.

The results of your HbA1c test are shown in 2 ways on the pathology report. They are expressed as a percentage (%) or as a value in mmol/mol.

(Do not confuse mmol/mol with your home blood glucose check which is measured in mmol/l)

Mmol/mol has been added to your pathology result because it is the international way of measuring HbA1c.

The table below shows a comparison of HbA1c and blood glucose levels:

HbA1c % HbA1c mmol/mol Average blood glucose level over the past 2-3 months
6% 42 mmol/mol 7.0 mmol/l
7% 53 mmol/mol 8.6 mmol/l
8% 64 mmol/mol 10.1 mmol/l
9% 75 mmol/mol 11.7 mmol/l
10% 86 mmol/mol 13.3 mmol/l
11% 97 mmol/mol 14.9 mmol/l
12% 108 mmol/mol 16.5 mmol/l


What blood glucose levels and HbA1c should I aim for?

Your diabetes health professional will recommend a blood glucose range and HbA1c that is suitable for you. They will consider your age, how long you have lived with diabetes, the diabetes medication you take, and any other relevant health conditions you may have.

The following ranges for blood glucose targets and HbA1c are a guide only. Talk to your diabetes health professionals about your individual targets.

Blood glucose targets
Fasting/ before meals Two hours after starting meals
Type 1 diabetes 4–8mmol/L <10mmol/L
Type 2 diabetes 6–8mmol/L 6–10mmol/L

HbA1c target

7.0% or 53mmol/mol

Me is all about what you need to do for yourself, managing your diabetes and doing what you can.

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