You can check your A1C through a standard blood test at a doctor’s office, a walk-in lab, or with an at-home finger-prick kit. No fasting is required, and the test can be done at any time of day regardless of when you last ate.
What the A1C Test Actually Measures
The A1C test measures the percentage of hemoglobin in your blood that has glucose attached to it. Hemoglobin is the protein inside red blood cells that carries oxygen. When blood sugar is elevated, glucose sticks to hemoglobin and stays there for the life of that red blood cell, roughly two to three months. So your A1C result reflects your average blood sugar over that entire window, not just a single moment in time. That’s what makes it more useful than a finger-stick glucose reading for understanding the bigger picture.
Three Ways to Get Tested
Doctor’s Office or Lab
The most accurate option is a laboratory blood draw, typically ordered by your doctor as part of routine bloodwork. Lab-based A1C tests are certified by the National Glycohemoglobin Standardization Program, which means they’re held to a strict accuracy standard. A doctor’s visit plus lab work typically runs $150 to $300 or more without insurance, though most insurance plans cover A1C testing, especially if you have diabetes or risk factors for it.
Walk-In Lab Services
If you don’t want to schedule a doctor’s appointment, several direct-to-consumer lab companies let you order an A1C test yourself. You pay online, visit a nearby lab location for a blood draw, and get results electronically. Prices hover around $50 with no insurance or doctor’s order needed. The blood still goes to a certified lab, so accuracy is comparable to what you’d get through your doctor.
At-Home Test Kits
Over-the-counter A1C kits are available at most pharmacies and online for about $35 to $65. These use a finger prick to collect a small blood sample, which you either read on the spot or mail to a lab. They’re convenient, but there’s a meaningful tradeoff in accuracy. Point-of-care A1C tests have lower sensitivity than lab-based methods. In one analysis, roughly 18% of people whose lab A1C was above 7% were missed by a point-of-care device. The FDA has stated that over-the-counter A1C tests should not be used to diagnose diabetes. They can be helpful for tracking trends between doctor visits, but they shouldn’t replace lab testing for clinical decisions.
What Your Results Mean
The American Diabetes Association uses these A1C ranges:
- Below 5.7%: Normal
- 5.7% to 6.4%: Prediabetes
- 6.5% or higher: Diabetes
A result in the prediabetes range means your blood sugar has been elevated but not high enough for a diabetes diagnosis. This is the stage where lifestyle changes, like adjusting your diet and increasing physical activity, can make the biggest difference. If your result is 6.5% or above, a second test is usually done to confirm the diagnosis before treatment begins.
No Fasting Required
Unlike a fasting glucose test, which requires you to skip food for 8 to 12 hours, the A1C test has no preparation. You can eat, drink, and take your medications as normal before the test. This is because A1C measures glucose that has been accumulating on red blood cells over months, so a single meal won’t move the number.
Conditions That Can Skew Results
Certain health conditions can make your A1C read falsely high or falsely low, even if your actual blood sugar control hasn’t changed. Iron deficiency anemia tends to push A1C results higher than they should be. Conditions that shorten the lifespan of red blood cells, like hemolytic anemia or significant blood loss, do the opposite and make A1C appear falsely low because the hemoglobin doesn’t have as long to accumulate glucose.
Hemoglobin variants, which are genetic differences in the structure of hemoglobin found more commonly in people of African, Mediterranean, or Southeast Asian descent, can also interfere with certain testing methods. Sickle cell trait and hemoglobin C trait are common examples. If you carry one of these variants, your doctor may need to use a specific type of A1C assay or rely on an alternative test called fructosamine or glycated albumin instead.
Pregnancy can also affect results. In late pregnancy, even women without diabetes tend to show slightly elevated A1C readings due to iron deficiency. Chronic kidney disease, especially in patients on dialysis, tends to make A1C underestimate actual blood sugar levels. If any of these situations apply to you, your A1C number alone may not tell the full story.
How Often to Test
If you have diabetes and your blood sugar is well controlled, testing twice a year is generally sufficient. If you’ve recently changed medications or your levels aren’t at target, testing every three months gives you and your doctor enough data to adjust your plan. For people with prediabetes, an annual A1C check is a reasonable way to monitor whether things are improving, stable, or progressing toward diabetes.
Since A1C reflects a two-to-three-month average, testing more frequently than every three months won’t give you meaningfully new information. The old red blood cells carrying glucose from your last testing window are still circulating, so the numbers overlap. Spacing tests at least 12 weeks apart gives you the clearest picture of change.