What is HbA1c test?

HbA1c, also called haemoglobin A1c, glycosylated haemoglobin or glycated haemoglobin, is a blood test primarily used to determine average blood sugar levels within 2-3 months.

Haemoglobin is a protein found inside RBC and it performs the vital function of carrying oxygen from the lungs to all parts of the body. Glucose in the blood enters red blood cells and binds to haemoglobin, forming glycated haemoglobin. The higher the blood glucose levels, the more the formation of glycated haemoglobin.

By measuring the amount of glycated haemoglobin (haemoglobin molecules with attached sugars), this test helps in assessing and monitoring blood sugar levels. Consequently, HbA1c test is useful in the diagnosis of type 2 diabetes and prediabetes and may be ordered in individuals who are suspected to have diabetes. It also helps in assessing the effectiveness of medications and lifestyle changes in controlling blood sugar levels.

  1. Why is HbA1c test performed?
  2. How do you prepare for HbA1c test?
  3. How is HbA1c test performed?
  4. HbA1c test results and normal range

HbA1c test  is performed in individuals who experience the following symptoms:

This test is also performed in individuals who may not be experiencing any symptoms, but are at a high risk of diabetes. Additionally, it is used for regular monitoring of blood sugar levels in individuals with diabetes and is commonly ordered in pregnant women to identify the risk of diabetes. As HbA1c gives an average of blood sugar levels for the past 2-3 months, it reflects sugar levels before as well as after conceiving in women who are in their first three months of pregnancy. This will help in the detection of undiagnosed pre-pregnancy diabetes.

This test is recommended every 3-6 months in individuals with diabetes to evaluate the effectiveness of antidiabetic therapy.

No special preparations or fasting is needed for this test. Normal eating and drinking can be continued before the test as foods and drinks do not affect results.

Some conditions like anaemia may affect the results of this test. Thus, it is important to inform the doctor about the presence of any such conditions. 

A small tourniquet is put around the arm, and a needle is inserted in the vein of the arm after swabbing the skin with an appropriate antiseptic. A blood sample is then withdrawn and collected into a sterile tube. Some pressure is applied at the site of injection after removing the needle to prevent further bleeding and to promote clotting.

This blood test has a slight risk of bruising at the site of injection. Bleeding is more commonly seen in individuals with impaired clotting. A feeling of faintness and dizziness might be experienced by some individuals. Such individuals should drink more water and sit for a while after this test. It is best to inform the physician if you notice any other discomforts.

HbA1c test results are indicated in the form of a percentage. Higher HbA1c levels indicate a higher blood glucose level. The risk of developing complications such as kidney or eye complications increases with an increase in HbA1c value.

Normal results:

An HbA1c level of less than 5.7% indicates the absence of diabetes and prediabetes.

Abnormal results:         

HbA1c level of 5.7% to 6.4% signifies prediabetes. HbA1c level of 6.5% and more indicates diabetes in individuals not previously diagnosed with diabetes.

Those with diabetes use A1c test to help manage their diabetes better. However, the results may be falsely low or high in individuals of Mediterranean, Southeast Asian or African descent. Such individuals may need to order a different type of A1c test.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.

Lab Tests recommended for HbA1C Test


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  1. American Diabetes Association [internet]; A1C and eAG
  2. National Call center network, Health direct [internet]: Department of Health: Australian government; HbA1c test
  3. Shariq. Sherwani, Haseeb A. Khan, Aishah Ekhzaimy, Afshan Masood, and Meena K. Sakharkar. Significance of HbA1c Test in Diagnosis and Prognosis of Diabetic Patients. Biomark Insights. 2016; 11: 95–104. Published online 2016 Jul 3. doi: 10.4137/BMI.S38440
  4. American Diabetes Association [internet]; Common Terms
  5. National Institute of Diabetes and Digestive and Kidney Diseases [internet]: US Department of Health and Human Services; The A1C Test & Diabetes
  6. National Call center network, Health direct [internet]: Department of Health: Australian government; Diabetes diagnosis
  7. American Diabetes Association [internet]; Diabetes Symptoms
  8. National Institute of Diabetes and Digestive and Kidney Diseases [internet]: US Department of Health and Human Services; Diabetes Tests & Diagnosis
  9. Health direct [internet]: Department of Health: Australian government; Guide to blood testing
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