What does it mean?
The Hb in the name stands for “haemoglobin,” and A1c refers to a specific portion of the four-part haemoglobin molecule. Haemoglobin molecules can be found within your red blood cells, carrying oxygen from your lungs to all the parts of your body. In fact, it is the pigment in haemoglobin that makes your blood red.

Because haemoglobin and red blood cells have a life span of up to four months, they can provide a clear picture of what has been happening in your system over a longer period of time.

How does it work?
As blood travels throughout your body, blood glucose (glucose) molecules attach themselves to the haemoglobin molecules. When this happens, the haemoglobin is glycated. The higher your blood glucose level, the greater number of haemoglobin molecules that will become glycated.

Once a haemoglobin molecule has glucose attached, it will stay glycated for the life of that red blood cell. So if you take a blood sample today, you will get a mix of brand-new cells and some that have been around for a few months. When you measure the number of glycated haemoglobin molecules, you get an average based on roughly the past three months.

What do the results tell you?
In a person who does not have diabetes, around 5 percent of the haemoglobin molecules will have glucose attached to them at any given time. At diagnosis, people with diabetes generally average two to three times more haemoglobin molecules with glucose attached to them—10.9 to 15.5 percent.

The European Association for the Study of Diabetes (EASD) recommends a target HbA1c of 7 percent or less. For every percentage point higher your HbA1c climbs, your risk of diabetes-related complications rises substantially.

How often should you be tested?
The Australian national recommendations are to test HbA1c four times a year or when there has been a change in treatment planning.

Of course, just like a single blood glucose self-test, you cannot look at HbA1c results alone. Since it is an average, a person who has frequent highs and lows can have a normal-looking HbA1c. It is only when viewed next to a daily log that the whole picture becomes clear.

What is a normal HbA1c?
According to the American Diabetes Association (ADA), a normal HbA1c test result for a person without diabetes would be 5%. But for someone recently diagnosed with diabetes, it can be in the 10% to 15% range. However,  generally the recommended target for an HbA1c test result is 7% or lower. If yours is higher than that, every point that you can bring it down will significantly reduce your risk of long-term diabetes complications, such as nerve damage, eye disease and cardiovascular problems.

Getting tested—doing the right thing
It is important that you get your HbA1c tested regularly,-and four times a year if your blood glucose is not under control. However, your doctor should determine how many times you should be tested annually.

While an HbA1c test is a good long-term indicator of what is going on with your blood glucose levels, it should never replace self-monitoring. You should not go three months between HbA1c tests not knowing what your blood glucose is doing. An HbA1c test cannot provide you with a complete, daily picture. For instance, a person with frequent highs and lows could average out to a normal looking HbA1c. That person would never know there was a problem unless he or she looked at blood glucose tests every day.