Is A1c test fasting necessary?

Medically reviewed by Neka Miller, PhD on March 25, 2021. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.


If A1c testing (also called HbA1c testing) has been mentioned or recommended to you by your healthcare provider, you may have a lot of questions. You might be wondering what the A1c blood test is and what it involves. Not only that, but you might also have questions about how to prepare for this specific kind of test.

One common question is whether A1c test fasting is necessary beforehand. Read on to learn more about the A1c test, what you do and don’t need to do to prepare for it, and what you can expect from the test.


Easily check your HbA1c level, an indicator of one’s blood sugar level over the past 3 months, from the comfort of home with the at-home HbA1c test.


What can the HbA1c test for?

When it comes to ways for testing for diabetes or prediabetes, the A1c test is one of the best methods available. It can also help you to monitor your condition if you already have a diabetes diagnosis.

Prediabetes means you have a high blood glucose level that could lead to diabetes later. Diabetes mellitus refers to type 1 diabetes and type 2 diabetes. With type 1 diabetes, your body doesn’t make enough insulin. In contrast, when you have type 2 diabetes your body can’t properly use the insulin that it makes.

Related: What is HbA1c?

While the HbA1c test can diagnose these conditions, it does have some limitations.

  • This test cannot diagnose gestational diabetes, or diabetes that develops during pregnancy.
  • The HbA1c test also isn’t an acceptable tool to diagnose diabetes in children.
  • Moderate to severe anemia can increase your HbA1c level, so the A1c test is not an effective diabetes screening tool if you have anything more than mild anemia.

However, in most cases, the A1c test is an effective tool for diagnosing and monitoring prediabetes and diabetes.

Is fasting required for an A1c test?

Blood, or plasma, glucose levels don’t remain the same throughout the day. Instead, they fluctuate, especially after a meal. However, this doesn’t affect HbA1c testing.

Unlike various other tests for diagnosing or evaluating diabetes, such as the oral glucose tolerance test, fasting is not required with the A1c test. The reason why is simple. This blood glucose test measures your average blood glucose level over the last 90 days, rather than providing a snapshot of your fasting blood glucose level at a particular moment.

For this reason, you do not need to do A1c test fasting, and you can eat and drink as you normally would before the test.

It’s important to note that the HbA1c test is not a replacement for regular blood glucose monitoring (using a glucometer) in people with diabetes.

What are the advantages of the HbA1c test?

Researchers and healthcare providers have found several unique benefits of using the A1c test. One of the main advantages is that you don’t have to fast before the test. However, that’s not the only one.

  • Acute stress can increase glucose production and interfere with how the body uses insulin. If you’re feeling nervous before a diabetes test that requires fasting, it can artificially inflate your blood sugar levels. In contrast, acute stress doesn’t affect HbA1c levels because the test examines your average glucose level over the last 90 days.
  • Exercising the night or morning before a fasting diabetes blood test can interfere with the test results and produce artificially lower blood glucose levels. However, exercise doesn’t have this effect on A1c testing, so you get a more accurate measure.

How does HbA1c testing work?

You can visit your healthcare provider to take an A1c test. The only thing that you need to do to prepare for it is to schedule an appointment. On the day of the test, you can expect to visit your healthcare provider so that you can provide a blood sample. Depending on your provider, you will either give this sample using a blood draw or a finger prick.

  • During a blood draw, you can expect a team member to place a small, thin needle into a vein in your arm. After taking the blood sample, it will be sent to a laboratory for HbA1c testing.
  • With a finger prick, you’ll have the tip of your finger pricked by a small, pointed lancet. In some cases, blood from a finger prick can be analyzed in your healthcare provider’s office. This means that you may get your results on the same day.

There are no activity restrictions after A1c testing. In fact, you can resume your usual activities immediately after having a blood draw or a finger prick.

In addition to visiting your healthcare provider for HbA1c testing, you can also choose to order an at-home test like the Everlywell HbA1c Test. Many people like this test because it can be taken in the convenience and privacy of home, with only a small blood sample required (collected with a simple finger prick).

After providing the blood sample for your at-home HbA1c kit, you’ll send it to a laboratory for testing. Once the analysis is finished, you’ll receive a secure, online report with your A1c results that you can share with your healthcare provider or diabetes care team.

What do my HbA1c results mean?

In general, the following HbA1c ranges indicate whether you have a normal blood sugar level, prediabetes, or diabetes.

  • Your blood sugar level is normal (optimal) if it is below 5.7%
  • You have prediabetes (suboptimal) if your level is between 5.7% and 6.4%
  • You have diabetes (elevated) if your level is 6.5% or higher

However, there are exceptions to the general ranges above, so it’s always best to discuss your particular A1c test results with your healthcare provider.

Is the Everlywell HbA1c Test a good option for me?

Our HbA1c Test is a great option if you’re looking for a convenient and easy way to see how well your blood sugar has been controlled over the last 90 days. Our at-home HbA1c Test only requires a small blood sample from a quick finger prick. All you do is prick your finger and mail your sample to a certified laboratory using a prepaid shipping label.

When your results are ready, you’ll receive a secure digital report that’s easy to understand. You’ll get to see how well your blood sugar levels—as indicated by HbA1c—have been controlled over the last three months, and can choose to share your results with your healthcare provider to start a conversation with them about recommended next steps.


References

1. What is diabetes. International Diabetes Federation. URL. Accessed March 25, 2021.

2. Hemoglobin A1C (HbA1c) Test. Medline Plus. URL. Accessed March 25, 2021.

3. Bonora E, Tuomilehto J. The pros and cons of diagnosing diabetes with A1C. Diabetes Care. 2011;34 Suppl 2(Suppl 2):S184-S190.

4. Katwal PC, Jirjees S, Htun ZM, Aldawudi I, Khan S. The Effect of Anemia and the Goal of Optimal HbA1c Control in Diabetes and Non-Diabetes. Cureus. 2020;12(6):e8431. Published 2020 Jun 3.

5. A1C test. Mayo Clinic. URL. Accessed March 25, 2021.

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