What is the HbA1C Test?

The hemoglobin A1c (HbA1c), is a blood test that measures the average blood sugar levels over the past 2–3 months, which makes it more reliable than other sugar tests that may be directly affected by food, drink, or daily fluctuations. (1)

HbA1c test measures the percentage of your red blood cells that have glucose-coated hemoglobin; When sugar enters the bloodstream, it attaches to hemoglobin, the higher the blood sugar levels, the more hemoglobin becomes coated with glucose. Since red blood cells have an average lifespan of about three months, this test provides an overview of blood sugar levels over that period.

Why Get Tested?

The HbA1C test is used for diagnosing diabetes or monitoring treatment plans in diabetics. (2)

How To Prepare?

No special preparation is required for the HbA1C test. It does not require fasting or dietary restrictions. (2)

How is it Performed?

The HbA1C test is a simple blood test conducted by drawing a blood sample from a vein in your arm. (2)

Interpreting Results

For Non-Diabetics

The HbA1C test provides a comprehensive view of average blood sugar levels rather than a single momentary reading. Results are generally interpreted as follows: (3)

• Normal: Below 5.7%.
• Prediabetes: Between 5.7% and 6.4% (This indicates a higher risk of developing diabetes in the future).
• Diabetes: 6.5% or higher. (A second confirmatory test is usually requested by your doctor to ensure the diagnosis is accurate).

For Diabetic Patients (Monitoring Treatment)

The HbA1C test is highly effective in assessing diabetes management in patients. (3)

• If the level is below 7%, it generally indicates good control of diabetes.
• If the level exceeds 7%, it may suggest that the treatment plan needs adjustments, such as:some text
  • Improving dietary habits.
  • Increasing physical activity.
  • Adjusting medication dosages or introducing new medications.

As a diabetes patient, aim to keep your HbA1C level below 7% (unless your doctor sets a different target based on your health condition). Higher HbA1C levels increase the risk of long-term complications, including damage to the heart, kidneys, eyes, and other organs. (3)

How to calculate average blood sugar from HbA1c?

The table below shows how HbA1C percentages correspond to estimated average glucose levels:

How Often to Test HbA1c?

The frequency of HbA1C testing depends on the patient’s condition and the doctor’s recommendations. Generally, these are the current recommendations of the American Diabetes Association (ADA) (3)

• For diabetics: Every 3–6 months, depending on blood sugar control.
• For individuals with prediabetes: Annually.
• For healthy adults: Since diabetes is often "silent," it is advised to screen all adults starting at age 35. If the results are normal, testing should be repeated at least every three years. Earlier and more frequent testing may be necessary for those with risk factors such as obesity or a family history of diabetes.

Factors Affecting Test Accuracy

Certain factors can impact the accuracy of HbA1C results: (1)

• Anemia caused by iron, vitamin B12, or folic acid deficiency.
• Significant blood loss before testing.
• Recent blood transfusions.
• Pregnancy.
• Hemoglobin disorders or the presence of variant hemoglobin types (e.g., thalassemia or sickle cell anemia).

If you need an HbA1C test or help managing diabetes, visit our Endocrinology Department. Our team will guide you to better health. Book your appointment today!

References

1. cdc - Testing for Diabetes and Prediabetes: A1C
2. MedlinePlus - Hemoglobin A1C (HbA1c) Test‍
3. diabetes journals - 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2024