A healthy A1C is below 5.7%. This number represents the percentage of your red blood cells that have sugar attached to them, giving a snapshot of your average blood sugar over the past two to three months. If you have diabetes, the target shifts higher, and the right number depends on your age, health, and treatment.
What A1C Numbers Mean
A1C falls into three categories:
- Normal: below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or above
Within the prediabetes range, risk isn’t flat. Someone at 6.3% is significantly closer to developing type 2 diabetes than someone at 5.8%. That sliding scale matters because prediabetes is the stage where lifestyle changes (losing 5 to 7% of body weight, regular physical activity) are most effective at preventing or delaying a diabetes diagnosis.
How A1C Translates to Daily Blood Sugar
A1C percentages can feel abstract. What helps is converting them to an estimated average glucose, the number you’d see on a blood sugar meter. The conversion works like this: multiply your A1C by 28.7, then subtract 46.7. That gives you a value in mg/dL.
Here’s what common A1C levels look like in everyday blood sugar terms:
- 5.7% A1C: roughly 117 mg/dL average
- 6.5% A1C: roughly 140 mg/dL average
- 7.0% A1C: roughly 154 mg/dL average
- 8.0% A1C: roughly 183 mg/dL average
- 9.0% A1C: roughly 212 mg/dL average
Keep in mind that A1C is an average. Two people can have the same A1C but very different daily patterns. One person’s blood sugar might stay steady around 154 mg/dL, while another’s swings between 80 and 230. Both could show a 7.0% A1C. That’s why many doctors look at A1C alongside daily glucose readings rather than relying on one number alone.
The Target for Adults With Diabetes
The American Diabetes Association sets a general goal of below 7% for most non-pregnant adults with diabetes. At this level, the risk of diabetes-related complications to the eyes, kidneys, and nerves drops substantially compared to higher levels. But 7% is a starting point, not a universal rule. Your doctor may set a tighter or looser target based on how long you’ve had diabetes, what medications you take, and whether you’re prone to episodes of low blood sugar.
A tighter target (closer to 6.5%) might make sense for someone recently diagnosed with type 2 diabetes who manages well with diet and a single medication. A looser target (7.5% to 8%) might be more appropriate for someone who has had diabetes for decades and takes insulin, because pushing too aggressively toward a lower number can increase the frequency of dangerous low blood sugar episodes.
Targets During Pregnancy
If you’re pregnant and have type 1 or type 2 diabetes, the target tightens considerably. The American College of Obstetricians and Gynecologists recommends keeping A1C at or below 6%. High blood sugar during pregnancy raises the risk of complications for both the mother and the baby, including preterm delivery and larger-than-expected birth weight. A1C is typically checked every four to six weeks during pregnancy to track whether blood sugar management is on course.
Targets for Children and Teens
For children and adolescents with type 1 diabetes, the current recommendation is an A1C below 7.5%. This is a single target for everyone under 18, which is simpler than older guidelines that varied by age group (previously, kids under 6 had a target below 8.5%, and those 6 to 12 had a target below 8%). The shift reflects growing evidence that tighter control in younger patients reduces long-term complications without unacceptably increasing the risk of low blood sugar, especially as glucose monitoring technology has improved.
Why Targets Change for Older Adults
For older adults with diabetes, A1C targets get more flexible. What matters most isn’t age itself but overall health, independence, and how a person’s medications affect their risk of low blood sugar. Low blood sugar in older adults is particularly dangerous because it can cause falls, confusion, and hospitalizations.
For older adults who are healthy and independent, the target stays around 7% or below when they’re on medications that don’t typically cause low blood sugar. If they take insulin or certain other medications that carry a higher risk of dropping blood sugar too low, a target between 7.1% and 8% is often more appropriate.
For those who need daily help with activities or who live with dementia, targets relax further, up to 8.5%. At this stage, the goal shifts from preventing long-term complications to avoiding symptoms right now: keeping blood sugar high enough to prevent dangerous lows but low enough to prevent excessive thirst, frequent urination, and other symptoms of very high blood sugar.
How Often to Get Tested
If you don’t have diabetes, A1C is typically part of routine screening, especially after age 45 or if you have risk factors like a family history, excess weight, or a sedentary lifestyle. If you have diabetes, you should get an A1C test at least twice a year. Your doctor may test more frequently if your treatment has recently changed, if your blood sugar has been difficult to control, or if you’re working toward a new target.
Because A1C reflects a two-to-three-month average, testing more often than every three months won’t give you meaningfully new information. The red blood cells the test measures have a lifespan of about 120 days, so each test overlaps somewhat with the previous one.
When A1C Can Be Misleading
A few conditions can make A1C readings inaccurate. Anything that changes the lifespan of your red blood cells will skew results. Iron-deficiency anemia, for example, causes red blood cells to live longer, which can push A1C readings artificially high. Conditions that destroy red blood cells faster than normal, like sickle cell trait or certain kidney diseases, can make A1C appear falsely low.
Recent blood loss or blood transfusions also throw off the test. If you have any of these conditions, your doctor may rely more heavily on other measures of blood sugar control, such as fructosamine testing or continuous glucose monitor data, rather than A1C alone. If your A1C doesn’t match what your daily glucose readings suggest, that mismatch is worth bringing up at your next visit.