What is HbA1c Test?

The term HbA1c refers to glycated haemoglobin. It typically develops when haemoglobin joins with glucose in the bloodstream, becoming ‘glycated.’ It is also known as haemoglobin A1c. By measuring glycated haemoglobin (HbA1c), doctors can get an overall picture of average blood sugar levels over a period of weeks/months. An HbA1c test is an important blood test that gives a good indication of how well an individual’s diabetes is being controlled. Together with the fasting plasma glucose test, the HbA1c test is one of the main methods in which type 2 diabetes is diagnosed.


How does HbA1c give an accurate measurement of average blood glucose?


When the body processes sugar, glucose naturally attaches to haemoglobin in the bloodstream. This bonding of glucose and haemoglobin is known as glycation. The amount of glucose combined with this protein (haemoglobin) is directly proportional to the total amount of sugar that is available in the system at that time. Because red blood cells in the human body survive for approximately 120 days before renewal, measuring glycated haemoglobin (or HbA1c) can be useful in reflecting the average blood glucose levels over that duration, providing a beneficial longer-term gauge of blood glucose control.


What is it used for?


HbA1c test is ordered to check for diabetes or prediabetes in adults. Prediabetes is the condition in which the blood sugar levels show an individual is at the risk of getting diabetes.
If anyone already has diabetes, an HbA1c test can help monitor their condition and glucose levels.


Limitations of HbA1c tests


HbA1c tests are usually reliable, but at the same time, there are some limitations to the accuracy of the test. For example, individuals with forms of anaemia may not have sufficient haemoglobin levels for the test to be accurate and may need to have a fructosamine test additionally.


Being pregnant or having an uncommon form of haemoglobin (called haemoglobin variant) can also lead to an inaccurate HbA1c. At the same time, readings can also be affected by short term issues such as illness since they can cause a temporary rise in blood glucose.


Because the HbA1c test measures blood sugar, if anyone is having higher blood sugar levels in the days leading up to the HbA1c test, this will have a more significant impact on the test result than the glucose levels 2 to 3 months before the test.


Why do an individual need an HbA1c test?


Individuals may need an HbA1c test if they have symptoms of diabetes. Symptoms include:


  • Increased thirst
  • Increased urination
  • Blurred vision
  • Fatigue


Many health care providers may also order an HbA1c test if anyone is at higher risk for getting diabetes. Risk factors include:


  • Being overweight or obese
  • High blood pressure
  • History of heart disease
  • Lack of physical activity


What happens during an HbA1c test?


A healthcare professional or technician will collect a blood sample from a vein in the arm using a needle. After the needle is inserted in the vein, a small amount of blood will be taken into a test tube or vial. An individual may feel a little sting when the needle goes in or out. The process usually takes less than five minutes.


Will an individual need to do anything to prepare for the test?


There is no need for any special preparations for an HbA1c test.





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