Written by the Doctobip Editorial Team. Educational information only — not medical advice. See our Medical Disclaimer.
If you’ve had a diabetes screening or checkup, you’ve probably seen “A1C” on your lab results. This single number tells a powerful story: your average blood sugar over the past two to three months. Here’s how to read it — and what you can do about it.
What is the A1C test?
The A1C test (also called hemoglobin A1C or HbA1c) measures the percentage of your red blood cells’ hemoglobin that has glucose attached to it. Because red blood cells live about three months, the test reflects your average blood sugar over that period — unlike a fingerstick, which is a snapshot of a single moment.
What do the numbers mean?
- Normal: below 5.7%
- Prediabetes: 5.7% – 6.4%
- Diabetes: 6.5% or higher (confirmed by repeat testing)
For many adults already living with diabetes, care teams commonly aim for an A1C below 7%, but your personal target may differ based on age, health conditions and treatment. See how A1C fits with daily numbers in our guide to normal blood sugar levels.
A1C and estimated average glucose
Labs often translate A1C into “estimated average glucose” (eAG). Roughly: an A1C of 6% ≈ 126 mg/dL average; 7% ≈ 154 mg/dL; 8% ≈ 183 mg/dL. It’s the same information, expressed in the units you see on your meter.
How often should A1C be checked?
- No diabetes, but risk factors: as part of periodic screening, per your doctor
- Prediabetes: typically every 1–2 years
- Diabetes, stable and at target: about twice a year
- Diabetes, treatment changed or above target: often quarterly
What can affect A1C accuracy?
Certain conditions can skew results — anemia, some hemoglobin variants, recent blood loss or transfusion, kidney disease, and pregnancy. If your fingerstick numbers and A1C don’t match, tell your doctor; another test may be more appropriate for you.
How to lower your A1C
A1C improves when day-to-day blood sugar improves. The pillars are the same as good diabetes management: balanced eating with attention to carbohydrates, regular physical activity, weight management, medication as prescribed, and consistent monitoring. Small changes sustained over months move the number — read our tips on exercise with diabetes and the best foods for diabetes.
- A1C shows your average blood sugar over ~3 months.
- Below 5.7% is normal; 6.5%+ suggests diabetes.
- Common target with diabetes: below 7% — but it’s individual.
- Consistent daily habits are what move the number.
Frequently asked questions
Do I need to fast before an A1C test?
No. A1C can be measured at any time of day, fasting or not.
How fast can A1C change?
Because it reflects ~3 months, meaningful change typically shows after 2–3 months of improved control.
Is A1C enough on its own?
It’s an average — it can hide highs and lows. Many people combine it with a meter or CGM. Learn more in our CGM guide.
References
- American Diabetes Association (ADA) — diabetes.org
- CDC — cdc.gov/diabetes
- NIDDK — niddk.nih.gov
Medical disclaimer: This article is for general education and is not a substitute for professional medical advice. Always consult a qualified healthcare provider.