You can check your A1C through a standard blood draw at a lab, a quick fingerstick at a doctor’s office, or an at-home test kit you use yourself. No fasting is required. The test measures how much glucose has attached to your red blood cells over the past two to three months, giving you a snapshot of your average blood sugar that a single glucose reading can’t provide.
What the A1C Test Actually Measures
Glucose in your bloodstream naturally sticks to hemoglobin, the protein inside red blood cells that carries oxygen. The more glucose circulating in your blood, the more hemoglobin gets coated. Since red blood cells live about three months, measuring the percentage of hemoglobin with glucose attached reveals your average blood sugar over that entire window. That’s why a single high or low day won’t dramatically shift the number.
Results fall into three ranges set by the American Diabetes Association. Below 5.7% is normal. Between 5.7% and 6.4% indicates prediabetes. At 6.5% or higher, the result meets the threshold for diabetes. These cutoffs apply to lab-certified tests, not necessarily every home device.
Option 1: Lab Blood Draw
The most accurate way to check your A1C is a venous blood draw at a lab. A technician inserts a needle into a vein in your arm and collects a sample, which is then analyzed using standardized methods. Results typically come back within five to seven business days. This is the gold standard that diagnostic cutoffs are based on, and it’s the version your doctor will use to make treatment decisions or confirm a diagnosis.
You can get a lab A1C ordered through your primary care provider, an endocrinologist, or in some cases through direct-to-consumer lab services that let you order bloodwork online and visit a nearby draw site. If your doctor is also checking cholesterol or other markers at the same appointment, those tests may require fasting, so ask ahead of time even though the A1C itself does not.
Option 2: Point-of-Care Test at a Clinic
Many doctor’s offices and clinics use point-of-care devices that deliver an A1C result from a fingerstick in just a few minutes. This is convenient because you get your number during the appointment and can discuss it immediately. However, these rapid devices are less precise than lab tests. A 2017 review of 61 studies comparing 13 point-of-care A1C devices to lab methods found that all 13 showed some degree of bias, with most reading slightly lower than the true lab value. In follow-up evaluations, a majority of tested devices failed to meet the accuracy standards set by the national certification program.
Point-of-care results are useful for tracking trends over time, but a result near a diagnostic boundary (say, 6.4% vs. 6.5%) should be confirmed with a full lab draw before any major changes to your care.
Option 3: At-Home A1C Kits
Over-the-counter A1C kits are available at pharmacies and online. The most common type, like the A1CNow Self Check, gives you a result at home in minutes without mailing anything to a lab. Here’s what the process looks like:
- Store the kit properly. Keep it at room temperature (64 to 77°F) and away from direct sunlight. If you refrigerate it, pull out the analyzer device, a shaker pouch, and a test cartridge at least one hour before testing so everything reaches room temperature.
- Collect a blood sample. Each kit includes a lancet to prick your fingertip and a small blood collector. Open one of the shaker pouches and follow its instructions to prepare the sample.
- Insert the sample quickly. You need to place your blood sample into the analyzer within two minutes. Once inserted, don’t move or pick up the device until it finishes processing.
- Read and record your result. The number appears on the device’s screen after a few minutes. Write it down immediately. The device does not save the reading after about 15 minutes.
Home kits are helpful for monitoring trends between doctor visits, but they carry the same accuracy limitations as other point-of-care devices. They are not a substitute for a lab test when a formal diagnosis is at stake.
How Often to Test
How frequently you should check depends on your risk profile. If you have no symptoms and no risk factors, screening is recommended starting at age 35, with repeat testing every three years if results are normal. If you’re overweight or obese and have additional risk factors like a family history of diabetes, high blood pressure, or a history of gestational diabetes, testing should start earlier regardless of age.
If your A1C already falls in the prediabetes range (5.7% to 6.4%), the recommendation is to test every year. People with diagnosed diabetes typically get tested two to four times per year depending on how stable their blood sugar management is. Weight gain or other changing risk factors are reasons to test sooner than your next scheduled check.
Conditions That Skew Results
Because the test depends on hemoglobin and red blood cell lifespan, anything that disrupts either one can throw off your number. Conditions that shorten how long red blood cells survive, such as hemolytic anemia, recent significant blood loss, or blood transfusions, will make your A1C appear falsely low. Iron deficiency anemia pushes the result in the opposite direction, making it appear falsely high.
Genetic hemoglobin variants like sickle cell trait or hemoglobin C trait can also interfere with accuracy, depending on the testing method used. Kidney failure, liver disease, certain medications (including opioids and some HIV drugs), and pregnancy can all shift results in either direction. If you have any of these conditions, your doctor may use an alternative measure of blood sugar control, such as a fructosamine test, which reflects a shorter two-to-three-week window and doesn’t depend on hemoglobin.
Making Sense of Your Number
A single A1C result is a starting point, not a verdict. The value reflects an average, which means it can mask wide swings. Someone whose blood sugar bounces between very high and very low could end up with the same A1C as someone whose levels stay steady in the middle. If your result surprises you in either direction, context matters: recent illness, medication changes, or one of the interfering conditions listed above could all play a role.
For people already managing diabetes, the general treatment target is an A1C below 7%, though individual goals vary based on age, other health conditions, and risk of low blood sugar episodes. Tracking your A1C over multiple tests gives you a far clearer picture than any single reading. A lab result every three to six months, supplemented by home kits if you want more frequent checks, is a practical approach for staying on top of the trend.