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MYMEALAID · PREDIABETES & PREVENTION

What Does A1C Measure?

Written by Momena Sohail

Reviewed by Mariam Ismail, RD, PhD

An A1C test is a blood test that measures your average blood sugar (glucose) levels over the past two to three months. It helps healthcare professionals check for prediabetes and diabetes, as well as monitor blood sugar management in people who already have diabetes.

How Does A1C Work?

Sugar in your bloodstream naturally attaches to a protein in your red blood cells called hemoglobin. The A1C test measures the percentage of hemoglobin that has sugar attached to it.

When blood sugar levels stay higher over time, more sugar is attached to hemoglobin, resulting in a higher A1C percentage. Unlike a random blood sugar test, which shows your glucose level at any time of the day, regardless of when you last ate, A1C provides a broader picture of your blood sugar over several months.

What Do A1C Results Mean?

A1C results are reported as a percentage. In general, a higher percentage means higher average blood sugar levels.

  • Below 6.0%: Below the Diabetes Canada A1C prediabetes threshold.
  • 6.0% - 6.4%: In the prediabetes range.
  • 6.5% or higher: In the diabetes range. A healthcare professional may need to confirm the result with repeat or additional testing.

These ranges help healthcare professionals assess blood sugar levels and determine whether further testing or support is needed. Your results should always be interpreted in the context of your health and medical history.

Do You Need to Fast Before an A1C Test?

No! Unlike some other blood sugar tests, an A1C test generally does not require fasting. You can usually eat and drink as normal beforehand.

However, certain conditions, such as certain types of anemia or blood disorders, can affect the accuracy of A1C results. Your healthcare professional can help determine whether this test is appropriate for you.

Why is A1C Important?

A1C testing can help identify elevated blood sugar before symptoms appear. For people living with diabetes, it can also help show how well their current management plan is working over time.

Remember: An A1C result is one part of understanding your health. If your result is higher than expected, it does not mean you need to figure everything out on your own. A healthcare professional can explain what your results mean and discuss the next steps with you.

References:

  • Cleveland Clinic. (2022, November 22). A1C: What it is, test, levels & chart. https://my.clevelandclinic.org/health/diagnostics/9731-a1c
  • Mayo Clinic Staff. (2025, February 22). A1C test. Mayo Clinic. https://www.mayoclinic.org/tests-procedures/a1c-test/about/pac-20384643

Quick Knowledge Check

Choose an answer, then reveal the correct answer below.

1. What period does A1C reflect?

  1. One hour
  2. Two to three months
  3. Ten years
Reveal answer

Two to three months

2. What is the Canadian A1C prediabetes range?

  1. 6.0% to 6.4%
  2. 5.0% to 5.4%
  3. 7.0% to 8.0%
Reveal answer

6.0% to 6.4%

3. Does A1C usually require fasting?

  1. Yes, 24 hours
  2. Yes, 12 hours
  3. No
Reveal answer

No

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General nutrition education. This article does not replace individualized advice from a qualified healthcare professional.

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