A good A1C number for someone without diabetes is below 5.7%. If you already have diabetes, the general target is below 7%, though your ideal number depends on your age, overall health, and how long you’ve had the condition. The A1C test measures the percentage of your red blood cells that have glucose stuck to their surface, giving you a snapshot of your average blood sugar over the past two to three months.
What the A1C Ranges Mean
A1C results fall into three categories:
- Normal: below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or higher
These thresholds come from the National Institute of Diabetes and Digestive and Kidney Diseases, and any result used for a diabetes diagnosis needs to be confirmed with a second test unless you already have clear symptoms like excessive thirst, frequent urination, or unexplained weight loss.
A prediabetes result doesn’t mean diabetes is inevitable. It means your blood sugar has been running higher than normal and that lifestyle changes, particularly in diet and physical activity, can often bring it back down before it crosses the 6.5% line.
How the Test Works
Glucose in your bloodstream naturally sticks to hemoglobin, the oxygen-carrying protein inside red blood cells. The higher your blood sugar runs on a day-to-day basis, the more hemoglobin gets coated. Since red blood cells live about three months, the A1C test captures a rolling average of your blood sugar over that entire lifespan. That’s what makes it more useful than a single finger-stick reading, which only tells you what’s happening at that exact moment.
A1C Targets if You Have Diabetes
The American Diabetes Association recommends an A1C below 7% for most adults with diabetes. In practical terms, a 7% A1C translates to an estimated average blood sugar of about 154 mg/dL. Here’s how other A1C levels correspond to daily blood sugar averages:
- 6%: ~126 mg/dL
- 7%: ~154 mg/dL
- 8%: ~183 mg/dL
- 9%: ~212 mg/dL
- 10%: ~240 mg/dL
These conversions use a standard formula (28.7 × A1C − 46.7 = estimated average glucose), and many lab reports now print the estimated average glucose alongside your A1C percentage to make the number easier to relate to daily monitoring.
When a Higher Target Is Appropriate
A 7% target isn’t right for everyone. The ADA emphasizes that A1C goals should be individualized, and for some people, aiming too low creates more risk than benefit.
Older adults with significant health conditions generally do well with a target of 8% or below. For those who are frail, have cognitive decline, or have a life expectancy under 10 years, a target below 8.5% may be reasonable. The priority shifts from hitting a specific number to avoiding dangerous blood sugar swings, particularly low blood sugar episodes that can cause falls, confusion, or hospitalization.
Children and adolescents with type 1 diabetes typically share the same below-7% goal as adults, though their targets are reassessed as they grow. Managing A1C in kids requires balancing blood sugar control against the realities of unpredictable eating, activity levels, and growth hormones.
Why Going Too Low Can Be Risky
You might assume the lowest possible A1C is always the best, but aggressively pushing your number down increases the chance of hypoglycemia, where blood sugar drops dangerously low. Research published in PLOS ONE found that people with type 2 diabetes who experienced severe hypoglycemic episodes had the highest rates of death from all causes. Interestingly, the greatest mortality risk wasn’t in people with low average A1C levels. It was in people who had severe low blood sugar episodes while their overall A1C was 9% or higher, suggesting that large, erratic swings in blood sugar are more dangerous than a consistently moderate level.
Mild episodes of low blood sugar (slight shakiness, hunger, sweating that resolves quickly) did not carry the same mortality risk. The danger concentrates in severe episodes requiring outside help, which become more likely when medications are dosed aggressively to chase a lower number.
How Often to Get Tested
If your A1C is stable and you’re meeting your target, testing every six months is generally enough. If you’ve recently changed medications, adjusted your diet significantly, or your numbers have been above target, your doctor will likely recheck at three-month intervals. Testing sooner than every three months isn’t useful because it takes about 90 days for all your old red blood cells to be replaced with new ones that reflect your current blood sugar patterns.
When A1C Results Can Be Misleading
Certain conditions can skew your A1C in either direction, making the number unreliable as a measure of actual blood sugar control.
Anything that shortens the lifespan of red blood cells, like hemolytic anemia or recovery from significant blood loss, will make your A1C appear falsely low. Your red blood cells simply haven’t been around long enough to accumulate the expected amount of glucose coating. Chronic kidney disease, particularly in people on dialysis, can also cause A1C to underestimate true blood sugar levels.
On the other hand, iron deficiency anemia tends to push A1C readings falsely high. This is also relevant during late pregnancy, when iron deficiency is common and can inflate A1C even in women without diabetes.
Genetic hemoglobin variants, including sickle cell trait and hemoglobin C trait, can interfere with certain testing methods. If you carry one of these variants, your doctor may need to use an alternative test or a specific A1C assay designed to account for it. For people with sickle cell disease specifically, the combination of anemia, increased red cell turnover, and transfusions makes A1C particularly unreliable.
If your A1C results don’t match what your daily blood sugar readings are telling you, one of these factors could be the reason. Alternative markers like fructosamine or glycated albumin can provide a more accurate picture in these situations.