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What is a HbA1c EDTA blood test?

A HbA1c EDTA blood test, also known as a glycated hemoglobin test, is an important blood test that provides information about a person’s average blood sugar levels over the past 2 to 3 months. This test measures the amount of hemoglobin in the blood that has glucose attached to it, which is also called glycosylated hemoglobin or HbA1c.

What is HbA1c?

Hemoglobin is the protein in red blood cells that carries oxygen throughout the body. Glucose in the bloodstream can attach to hemoglobin, forming glycosylated hemoglobin or HbA1c. The more glucose in the blood, the more hemoglobin becomes glycosylated. Therefore, the HbA1c level reflects the average blood sugar levels over the past 2 to 3 months, which is the lifespan of a red blood cell.

Why test HbA1c?

The HbA1c test is used to:

  • Diagnose diabetes – An HbA1c of 6.5% or higher indicates diabetes.
  • Monitor diabetes treatment – The test is done regularly to evaluate how well blood sugar levels are being controlled.
  • Assess risk of diabetes complications – Higher HbA1c levels increase the risk of diabetic complications affecting the eyes, kidneys, nerves and heart.

The HbA1c test has several advantages over measuring glucose directly:

  • Provides an overview of blood sugar levels over a longer period rather than at a single point in time.
  • Does not require fasting and can be done at any time of day.
  • Less affected by temporary fluctuations in blood sugar.

When should the test be done?

The HbA1c test should be done:

  • At least twice a year in people with diabetes to monitor control.
  • Once a year in people at high risk of developing diabetes.
  • As part of an initial diabetes diagnosis.

It does not need any special preparation such as fasting. The test can be done any time of day. No prior dietary changes are required.

Understanding the results

HbA1c test results show the percentage of hemoglobin that is glycosylated. A normal HbA1c level is below 5.7%.

HbA1c Level Meaning
Below 5.7% Normal
5.7% to 6.4% Prediabetes
6.5% or higher Diabetes

In people with diabetes, the target HbA1c level is usually below 7%. Levels above 9% indicate very poor blood sugar control.

How is the test done?

The HbA1c test involves drawing a sample of blood, usually from the arm, by a health professional. An EDTA tube is used to collect the blood sample in order to prevent it from clotting. The blood is then sent to a laboratory for analysis. Results are generally available within a few days.

The HbA1c test does not require any specific preparations such as fasting. You can eat and drink normally before the test. The test is done any time during the day.

Effects of red blood cell age

Because HbA1c measures glucose bound to hemoglobin in red blood cells, factors that affect red blood cell lifespan may affect HbA1c levels. Conditions where red blood cells have a shorter lifespan (such as hemolytic anemia) can falsely lower HbA1c levels. Anemia and blood transfusions can also impact results.

Limitations of the test

While HbA1c provides useful information about overall blood sugar control, there are some limitations:

  • Does not show short-term fluctuations in blood sugars.
  • Levels may be inaccurate in certain blood disorders.
  • Does not detect hypoglycemic (low blood sugar) episodes.

For this reason, the HbA1c test should always be used together with daily self-monitoring of blood sugars. Fingerstick glucose checks provide important complementary information by showing glucose levels at specific times of day, such as before meals and at bedtime.

How to lower HbA1c levels

Here are some tips to help lower HbA1c levels:

  • Monitor blood sugar regularly and keep levels within target ranges.
  • Take all diabetes medications as prescribed.
  • Follow a healthy meal plan focused on complex carbs, fiber and lean protein.
  • Limit simple sugars and refined carbohydrates.
  • Stay active with regular exercise.
  • Aim for a healthy weight.
  • Don’t smoke – smoking raises blood sugar levels.
  • Work to reduce stress.
  • Get enough sleep and rest.

Making lifestyle changes and following the treatment plan outlined by your healthcare provider can help bring your HbA1c into the target range, reducing the risk of complications.

Risks and complications

Elevated HbA1c levels indicate poorer long-term blood sugar control and an increased risk of diabetes complications affecting:

  • Eyes – Diabetic retinopathy can cause vision loss and blindness.
  • Kidneys – Diabetic nephropathy can lead to kidney failure.
  • Nerves – Diabetic neuropathy causes pain, numbness and weakness.
  • Heart and blood vessels – Increased risk of cardiovascular disease, heart attack and stroke.

By maintaining HbA1c levels within target ranges, people with diabetes can reduce the risk of developing these dangerous complications.


The HbA1c blood test provides valuable information about a person’s average blood sugar levels over 2-3 months. This test is important for diagnosing diabetes, monitoring diabetes treatment and reducing the risk of complications. By making lifestyle changes and sticking to a treatment plan, people with diabetes can aim to keep their HbA1c levels in the target range for good health.