what is blood test hemoglobin a1c

The Hemoglobin A1C (HbA1c) test is a blood test that measures your average blood sugar (glucose) levels over the past 2 to 3 months. It is commonly used to diagnose prediabetes and diabetes, as well as to monitor how well your diabetes is being managed.

How It Works:

• Glucose in your blood attaches to hemoglobin, a protein in red blood cells.
• The A1C test measures the percentage of hemoglobin that is coated with glucose.
• Since red blood cells regenerate every 3 months, the test reflects your average blood sugar levels over that period.

A1C Ranges:

A1C Level Diagnosis

Below 5.7% Normal
5.7%–6.4% Prediabetes
6.5% or higher Diabetes

Why It’s Important:

• It provides a long-term view of blood sugar control.
• It helps healthcare providers adjust treatment plans for diabetes.

For more details, consult your healthcare provider or visit CDC's A1C Test Page.