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Hemoglobin A1c Blood Test

Last updated May 9, 2018

Approved by: Maulik P. Purohit MD, MPH

The Hemoglobin A1c Blood Test is an early screening process for diabetes (both Type 1 & Type 2) and prediabetes.

What are the other Names for this Test? (Equivalent Terms)

  • Glycated Hemoglobin Test
  • HbA1c Test
  • A1c & eAG (Estimated Average Glucose) Test

What is Hemoglobin A1c Blood Test? (Background Information)

  • The Hemoglobin A1c Blood Test is an early screening process for diabetes (both Type 1 & Type 2) and prediabetes
  • The test also helps monitor the course of diabetes treatment, where the average blood sugar (or glucose) quantity over a few months, is measured. This factor serves as a good indicator of the effectiveness of the treatment

What are the Clinical Indications for performing the Hemoglobin A1c Blood Test?

Individuals in the following categories, who are suspected of having diabetes, are primarily prescribed the Hemoglobin A1c Blood Test. They include those suffering from:

  • Frequent urination, called polyuria
  • An increased level of thirst, called polydipsia
  • An increased hunger, called polyphagia
  • Fatigue and weakness, nausea
  • Vision changes due to high blood sugar, blurred vision
  • Skin rashes
  • Wounds that heal very slowly

The test is also recommended for diabetics in order to monitor their blood sugar levels, at least twice a year. The periodicity of testing is increased, if diabetes is not under control.

How is the Specimen Collected for Hemoglobin A1c Blood Test?

Sample required: Blood

Process: Insertion of needle into a vein (arm) or, using the finger stick (finger prick) method in adults and children.

Preparation required: None

What is the Significance of the Hemoglobin A1c Blood Test Result?

There exists a mathematical relation between A1c and eAG. The ADA (American Diabetes Association) proposes that both be reported.

  • When the A1c & eAG test(s) is used to diagnose diabetes, a value for A1c of:
    • >6.5% indicates an incidence of diabetes
    • 5.7-6.4% indicates the occurrence of prediabetes (that forebodes a higher risk of future diabetes)
  • When it is used to manage diabetes, a value for A1c of:
    • <7.0% indicates that it is under fair control. This could be the targeted percentage level
    • >7.0% indicates that the current treatment measures are effective enough
  • High values for A1c, indicate severe risk of developing medical complications related to diabetes

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.

Additional and Relevant Useful Information:

  • There are limitations to the Hemoglobin A1c Blood Test, for the test is dependent upon blood hemoglobin levels
  • Any variation from the normal values due to conditions, such as severe bleeding, lack of sufficient iron in blood, presence of hemoglobin variants, etc. could hamper the regular test results

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

References and Information Sources used for the Article:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Sept. 4, 2013
Last updated: May 9, 2018