A1C vs. Estimated Average Glucose (eAG)
Understanding blood sugar can be confusing because there are two ways to measure it. Think of it like taking a photo versus watching a movie.
Glucose (The Snapshot)
This is your standard finger-stick test. It tells you your blood sugar level at that exact moment. It changes rapidly based on food, stress, or activity.
A1C (The Video)
A1C is the average of the last 3 months. Because red blood cells live for ~90 days, sugar sticks to them over time (glycation), creating a record of your long-term control.
A1C Risk Levels
The American Diabetes Association (ADA) uses these ranges to diagnose diabetes and prediabetes.
| Category | A1C Range | Avg Glucose (eAG) |
|---|---|---|
| Normal | < 5.7% | < 117 mg/dL |
| Prediabetes | 5.7% – 6.4% | 117 – 137 mg/dL |
| Diabetes | ≥ 6.5% | ≥ 140 mg/dL |
Frequently Asked Questions
My A1C is 6.0%. Do I have diabetes?
No, but you are in the Prediabetes range (the "Warning Zone"). This means your blood sugar is higher than normal but not yet high enough for a Type 2 diagnosis. Lifestyle changes like diet and exercise can often reverse this condition.
Why doesn't my eAG match my daily glucose meter?
Your meter measures "snapshots"—often when fasting or after meals. Your A1C/eAG is a 24/7 average, including when you sleep (when sugar is often lower). Therefore, eAG is usually lower than the numbers you see during the day.
How often should I test?
Typically every 3 to 6 months. Testing more frequently (e.g., every 2 weeks) is not useful because red blood cells take about 3 months to turn over, so the test won't show significant changes yet.
Tools & Data Verified by the EverydayCalculators Medical Research Team.
Last updated: January 2026.