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A Review of The A1c Test

November is National Diabetes Month. In honor of this very important month I would like to review the Hemoglobin A1c test (also referred to as A1c).

What is the A1c test?

  • The A1c test is a measure of your average blood glucose over the past 2 to 3 months.
  • The A1c test measures how much glucose attaches to the hemoglobin portion of red blood cells.
  • The higher the blood glucose is, the more glucose that will attach to hemoglobin, thus increasing A1c.
    • Hemoglobin is a protein in the red blood cell responsible for carrying oxygen body tissues.
    • Red blood cells are constantly forming and dying. The average lifespan of a red blood cell is 3 months.

Why is the A1c test done?

  • The A1c test can be done to diagnose diabetes and is also used to assess diabetes control for those with established diabetes.
  • The Diabetes Control and Complications Trials (DCCT) was a landmark study that showed that tight glycemic control, as measured by A1c, could reduce the risk of microvascular complications (such as retinopathy and nephropathy).

When is the test done?

  • The test can be done at any time of day and does not require fasting

How often should I have it done?

  • The 2015 Standards of Medical Care In Diabetes recommends:
    • “Perform the A1C test at least two times a year in patients who are meeting treatment goals (and who have stable glycemic control)."
    • “Perform the A1C test quarterly in patients whose therapy has changed or who are not meeting glycemic goals”

What are the target A1c ranges?

  • Normal: 4 to 5.6 %
  • Pre-diabetes: 5.7 to 6.4 %
  • Diabetes Diagnosis: >6.5 % (* Repeat testing should be done in the absence of absolute hyperglycemia)

A1c goal if you have diabetes:

The 2015 Standards of Medical Care In Diabetes recommends:

  • <7 % (for non-pregnant adults)
  • A lower goal, 6.5 %, may be recommended for those with short duration of type 2 diabetes, long life expectancy, treatment is either lifestyle changes or Metformin and there is no significant history of cardiovascular disease

How do I calculate my average blood glucose from my A1c test?

Estimated average glucose (eAG) is calculated as follows:

  • eAG= (A1c x 28.7) – 46.7
  • Example:
    • A1c: 8 %
    • eAG: 183
      • (8 x 28.7) – 46.7

What conditions may cause a falsely high or falsely low A1c test result?

  • False LOW A1c
    • Hemolysis (premature breakdown of red blood cells)
    • Certain hemoglobinpathies (inherited group of blood disorders)
    • Chronic liver disease
    • Chronic kidney disease
    • Recent blood transfusion
    • High triglycerides
    • Certain medications (make sure to keep your physician up to date on all your current medications)
  • False HIGH A1c
    • Iron deficiency
    • Vitamin B 12 deficiency
    • Alcoholism
    • Uremia (buildup of urea and other waste products in blood)
    • Hyperbilirubinemia (abnormally high level of bilirubin in the blood)
    • Certain medications (make sure to keep your physician up to date on all your current medications)

You might be asking, “What should I do with the above information?”

  • First things first, talk with your physician.
  • Ask your doctor about the A1c test. How often should you have the A1c test done and what is your A1c target (based on your current diabetes management)?
  • If you A1c is above target, ask your physician about lifestyle changes (i.e. diet, exercise) that may help lower A1c and if/when medication is indicated (if you are already on medication a change may be necessary to help you reach your goal).

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This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.

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