Diabetes mellitus is a worldwide problem and it is becoming more common in South Africa. Early diagnosis and intervention is very important. You may have had the odd finger prick blood sugar test but you will need more specialized investigations to diagnose diabetes and monitor your blood glucose levels. One of the tests that is the preferred option among doctors is the A1C test, also known as the HbA1C. What is being detected in this type of test is the glycated or glycosylated haemoglobin in your red blood cells.
What is HbA1C?
HbA1C, now more commonly referred to just as the A1C test, measures the amount of glucose (sugar) within the red blood cells. It gives your doctor an idea of how your blood glucose levels have been over the past 2 to 3 months. Traditional blood glucose tests indicate your glucose levels at a specific time period, usually at the time that the blood sample is taken. But an A1C test can give a more long term look at your blood glucose levels, essentially giving your doctor the ability to see what has been going on with your glucose levels for the past few months.
It is not always the preferred test for women who develop diabetes during pregnancy (gestational diabetes). In these cases diabetes may have started quite suddenly with the blood glucose levels having been normal in the months prior to testing. Therefore the result can be inaccurate in gestational diabetes. But A1C testing is ideal for diagnosing and monitoring type 1 and type 2 diabetes. For pregnant women, the oral glucose tolerance test (OGTT) specifically for pregnancy may be the preferred method of diagnosing gestational diabetes.
How does it work?
The red blood cells are the most abundant cells in your bloodstream. It is responsible for carrying gases like oxygen throughout the body. A specific compound within it, known as haemoglobin, is responsible for this oxygen-carrying capacity of the red blood cells. Sugar in your bloodstream may attach to these red blood cells over weeks and months. By measuring the amount of sugar attached to these cells, your doctor is then able to determine how your blood glucose levels have been for approximately 2 to 3 months.
It is useful in identifying abnormalities in glucose levels over the preceding months and aids with the diagnosis of diabetes mellitus. But it is even more useful in assessing how well you have been doing on diabetes treatment. Not all diabetics are disciplined when it comes to taking their medication as prescribed, adhering to a diabetic diet or exercising – all of these measures help to keep the blood glucose levels within a normal range or close to it. If you have not been doing all that you should to manage your diabetes, then an A1C will reveal it.
When should you test?
If you suspect that you have diabetes then you should speak to your doctor. The symptoms may be vague at the outset but changes in body weight, excessive thirst, frequent urination and alterations in appetite are some of the more common symptoms. If you are at a high risk of developing diabetes then your doctor may advise testing on a regular basis even if you have no symptoms. The oral glucose tolerance test (OGTT) is still preferred by many doctors for diagnosing diabetes mellitus but the A1C is an important part of diabetes monitoring.
Frequency Of Testing
Testing should be done at certain intervals for screening high risk individuals and for monitoring diabetics. Since the A1C test provides an indication of blood glucose levels for as long as 3 months, you do not have to test as frequently as you would with other blood glucose testing methods if you are a diabetic. The guidelines may vary but your doctor would advise testing at the following intervals depending on whether you are diabetic or not, are using certain diabetes medication and the history of your blood glucose control.
- Well managed type 2 diabetes mellitus where insulin is not being used – A1C testing should be done 2 time a year.
- Poorly controlled type 2 diabetes mellitus – testing should be done 4 times a year.
- Type 1 diabetes – A1C should be done 3 to 4 times a year.
- Type 2 diabetes with insulin use – A1 testing should be done 4 times a year.
If you are on medical aid then A1C testing may be mandatory at certain time levels as part of the chronic disease management program. You should discuss these requirements with your medical scheme and your doctor.
A1C Test Results
You doctor will take a blood sample from the vein of your upper arm or this may be done at the pathology laboratory. The blood sample is then sent to the laboratory for testing. The results may be ready within 1 to 3 days, depending on your location and whether it is being done at a government or private laboratory. The results will then be sent to your doctor. It will also assist your doctor in making changes in your diabetes management program.
The A1C results are expressed as a percentage. Diabetics should aim to keep the A1C levels at 7% or lower. Other results are as follows:
- Normal : 4.5% to 6%
- Prediabetes : 5.7% to 6.4%
- Diabetes : 6.5% or higher
Diabetics with poorly controlled diabetes may record levels as high as 8%. It is important to seek treatment from your doctor as very high levels means that diabetic complications affecting the heart and blood vessels, nerves, kidneys and eyes may develop in time.