Understanding your HbA1c test

What is the HbA1c test?

HbA1c is a blood test that reflects your average blood sugar over the past two to three months. It measures the proportion of hemoglobin—the protein in red blood cells that carries oxygen—with glucose attached. [1]

Clinicians use it to help identify prediabetes or type 2 diabetes, and to follow blood sugar management over time. [1]

Preparing for your test

HbA1c alone does not require fasting. If other blood tests are booked at the same time, check whether they require it. [2]

A clinician usually takes a small blood sample from your arm. Tell them about your medicines and any pregnancy. Keep taking prescribed medicines unless your clinician advises otherwise. [1]

Understanding the result

The percentage ranges below help clinicians diagnose prediabetes and diabetes. [2]

A diagnosis usually needs confirmation with a repeat HbA1c or another blood glucose test, particularly when there are no symptoms. [3]

Your target is personal

HbA1c gives a longer-term picture. It does not show every daily high or low, so continue any home monitoring agreed with your clinician. [4]

What can affect accuracy?

Some conditions can make HbA1c misleading. Tell your clinician about:

• Anemia, recent blood loss or a blood transfusion.
• Known hemoglobin variants or blood disorders.
• Kidney failure, liver disease or pregnancy.

If HbA1c does not match your glucose readings, your clinician may review the test method or use another test. HbA1c is not used to diagnose gestational diabetes. [3]

When should it be repeated?

Many people with diabetes have HbA1c checked at least twice a year. More frequent testing may be needed after treatment changes or when goals are not being met. Agree your next test date with your care team. [4]