Hemoglobin A1c: What It Is and What Your Results Mean
Bottom line: HbA1c measures your average blood sugar over 2-3 months. Normal is below 5.7%. It diagnoses and monitors prediabetes and diabetes.
What Is Hemoglobin A1c?
Hemoglobin A1c (HbA1c) measures your average blood sugar level over the past 2 to 3 months. Unlike fasting glucose, which captures a single moment, HbA1c reveals how well your blood sugar has been controlled over time.
The test works by measuring the percentage of hemoglobin proteins in your red blood cells that have glucose attached to them. Since red blood cells live for about 120 days, the HbA1c reflects your average glucose exposure over that period.
HbA1c is used to diagnose prediabetes and diabetes, and to monitor blood sugar management in people who already have diabetes. It does not require fasting, making it a convenient screening test.
Hemoglobin A1c Reference Ranges
| Classification | Range (%) |
|---|---|
| Below Normal | Below 5.0 |
| Normal | 4.0 - 5.6 |
| Prediabetes | 5.7 - 6.4 |
| Diabetes | 6.5 - 9.9 |
| Poorly Controlled Diabetes | 10.0 - 20.0 |
What Affects Your Hemoglobin A1c Levels?
- Diet and overall carbohydrate intake patterns
- Physical activity and exercise consistency
- Body weight and fat distribution
- Medication adherence for those on diabetes treatment
- Certain conditions like anemia or hemoglobin variants can affect accuracy
- Pregnancy and kidney disease may also influence results
When to Get Tested
If you have risk factors for diabetes, HbA1c should be tested at least every 3 years. If you have prediabetes, test annually. People with diabetes typically test every 3-6 months to monitor blood sugar control.
Look Up Your Hemoglobin A1c Result
Select your value below to see a detailed breakdown of what it means:
Below Normal
Normal
Prediabetes
Diabetes
Poorly Controlled Diabetes
Read the Full Blood Sugar Guide
Frequently Asked Questions
Below 5.7% is normal. 5.7-6.4% indicates prediabetes. 6.5% or higher indicates diabetes. For people managing diabetes, the ADA generally recommends a target below 7%.
Since HbA1c reflects a 2-3 month average, meaningful changes typically take at least 8-12 weeks of consistent lifestyle or medication adjustments to show up on the test.
HbA1c provides a broader picture of blood sugar control over time and is less affected by daily fluctuations. However, both tests together give the most complete assessment.
Commonly Seen Together
Blood test results rarely exist in isolation. When one marker is out of range, these related values are often checked alongside it: