How to Test Your A1C: Lab, Home Kits, and What Results Mean

The A1C test reflects your average blood sugar over the past two to three months. It's the gold standard for both diagnosing diabetes and tracking how well treatment is working.

How the test works

When glucose circulates in your blood, a small fraction attaches to hemoglobin — the oxygen-carrying protein inside red blood cells. The A1C test measures the percentage of your hemoglobin that has glucose bound to it. Because red blood cells live about 120 days, the test gives you a moving average of roughly the last 90 days.

You don't need to fast. You don't need to avoid anything the morning of the test. A single blood draw is all it takes.

How often should you test?

General guidelines

No diabetes, no risk factors: A1C isn't routinely needed, though it's often included in standard blood panels.
Prediabetes or risk factors: Once a year is typical.
Diabetes, well controlled: Every 6 months.
Diabetes, not at target or changing treatment: Every 3 months.

Your doctor may recommend a different schedule based on your individual situation. Pregnancy, certain medications, and recent blood loss or transfusion can all affect A1C and may change how often you test.

Where to get tested

At a clinic or lab

A conventional blood draw at your doctor's office or a commercial lab is the most accurate option. Results are typically available within a day or two and go directly into your medical record.

At home

FDA-cleared home A1C test kits have become more accessible and more accurate over the past decade. The most popular consumer option is the A1CNow SelfCheck, which delivers results in about five minutes from a fingerstick.

Home testing works well for people who want more frequent feedback between doctor visits, or who have trouble getting to a lab. If you use a home kit, stick with the same brand for consistency — different kits can have slightly different calibrations. See our guide to home A1C meters.

What your results mean

Normal Below 5.7%

No diabetes.

Prediabetes 5.7% - 6.4%

Elevated risk.

Diabetes 6.5% and above

Diagnostic of diabetes.

A1C vs. estimated average glucose (eAG)

Many lab reports now include eAG alongside A1C — the same information translated into the mg/dL numbers you see on a glucose meter.

A1C	eAG (mg/dL)	eAG (mmol/L)
5%	97	5.4
6%	126	7.0
7%	154	8.6
8%	183	10.1
9%	212	11.8
10%	240	13.4

Try our interactive A1C ↔ eAG calculator →

Practical tips for accurate results

Consistency matters. Test at the same lab — or with the same home kit — each time for meaningful comparisons.
No fasting required. Unlike glucose tests, A1C is not affected by what you ate that morning.
Combine with daily glucose monitoring if your doctor recommends it. A1C shows the average; daily readings or a CGM show the variability.
Consider conditions that skew results. Anemia, hemoglobin variants (common in people of African, Mediterranean, or Southeast Asian descent), recent transfusions, and some kidney conditions can make A1C less reliable.

This information is educational and not a substitute for medical advice. Testing frequency and interpretation should be individualized by your healthcare provider.