What is an HbA1c blood test

Updated On :

HbA1c Blood test gives your average blood glucose levels in the previous 2 to 3 months.

What is the full form of HbA1c ?

  • Hb in HbA1c refers to Hemoglobin 
  • A in HbA1c refers to Adult
  • A1c is the subtype of Adult Hemoglobin. Majority of hemoglobin in healthy adults is of A1c and other Hemoglobin variants are A1a, A1b, A1c and others.

HbA1c means Glycosylated Hemoglobin, and also called Glycated Hemoglobin, which means the sugar molecule is attached to Hemoglobin.

(Glycation refers to bonding of sugar molecules to a protein or lipid. In this case, the protein is Hemoglobin)

Hemoglobin transports oxygen and is found in RBCs or Red Blood Corpuscles, in the blood.

Why is the HbA1c Blood Test important?

As HbA1c is circulated within Red blood cells, whose lifespan is around 120 days, generally reflects the state of blood sugar in the preceding 8 to 12 weeks, thereby helping to assess glycemic control or to diagnose diabetes.

The Value of HbA1c is weighted by the most recent blood glucose levels ( previous month).

How often should the HbA1c Test be done?

Measurements should be done in 3 to 4 months intervals and in those who are self monitoring, it is helpful in knowing the accuracy and doctors use it in adjusting the dosage of the medications.

Procedure for HbA1c Test

Prior preparation such as fasting is not required for HbA1c test and can be done at any time of the day or night, even if you are in a well fed state.

Blood from the vein is collected in Sample collection Vial which is Purple coloured called the EDTA tube (EDTA is Ethylenediaminetetraacetic acid)

EDTA is chemical which is found in the sample collection tube, which binds to metal ions in the blood, like calcium, magnesium and iron and prevents the clotting of the blood in the tube)

Testing Methods of HbA1c 

HbA1c Test by High-performance liquid chromatography or HPLC method.

  • Less blood sample required
  • Precise
  • Rapid and takes around 20 minutes

What is HbA1c Normal Range?

The Normal Range of HbA1c is between 4% and 5.7% . Normal Healthy Adults have HbA1c below 5.7%. If it’s more, then read about Prediabetes.

Factors that interfere with HbA1C Blood Test Results

There is a possibility of the test results not showing correct values. The following factors interfere with the results.

Conditions which decrease Red Blood cell survival can falsely lower HbA1c levels, as we know that HbA1c is circulated within Red blood cells or Erythrocytes. 

  1. The accuracy of HbA1c results are affected by Hemoglobin Variants and in persons with hemoglobin F, low HbA1c values are seen. The frequently encountered hemoglobin variants can be seen on ngsp.org, which is the website for The National Glycohemoglobin Standardization Program.
  2. Acute blood loss and Hemolytic Anemia will show false lower HbA1c levels
  3. Intravenous iron and erythropoietin therapy for anemia in chronic kidney disease may show false lower hbA1c levels.
  4. Vitamin C and Vitamin E can lower HbA1c levels, possibly due to inhibition of Hemoglobin Glycation.

Conditions that increase Erythrocyte survival or Red blood cell survival, can increase HbA1c levels, which are

  1. Splenectomy for Hereditary Spherocytosis can false raise HbA1c levels
  2. Iron Deficiency Anemia

Question and Answers on HbA1c

1. What is the difference between FBS and HbA1c ?

Fasting Blood Sugar Test measures the plasma glucose when you fast for 8 to 10 hours or overnight, and the value denotes the presence of glucose on that day.

While HbA1c test values represent plasma glucose values in the preceding 8 to 12 weeks.

2. How to cheat HbA1c Test?

Why would you try to cheat on the HbA1c Test?  Individuals who have not yet come to terms that they are diabetic might cheat on Fasting Blood Glucose test or FBS Test, but in HbA1c Test, it is NOT possible as the test gives results which are average of preceding 8 to 12 weeks.

3. Is the HbA1c Test affected by meal intake?

No, the HbA1c test is NOT affected by meal intake.

4. How many hours Fasting before the HbA1c Test?

Fasting is NOT required before taking an HbA1c Test

5. Is the HbA1c test done in Empty Stomach?

The Test can be given at any time of the day or night. Giving it on an empty stomach or when you just had a meal has no effect on the test results.

6. Can I eat before the HbA1c Test?

Yes, You could .

7. Can I drink water before the HbA1c Test?

Yes! You can

8. Can the HbA1c test be done after Food?

Yes! It can be done after food.

Table of Contents

Updated On :