For most adults without diabetes, a healthy hemoglobin A1c is below 5.7%. If you have diabetes, the general target is below 7%. But the right number for you depends on your age, health status, and whether you’re pregnant, so the “ideal” A1c isn’t one-size-fits-all.
A1c measures the percentage of your red blood cells that have sugar attached to them. Because red blood cells live about three months, the test captures your average blood sugar over that window, giving a much broader picture than a single finger stick.
The Three Diagnostic Ranges
Doctors use A1c to sort results into three categories:
- Normal: below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or higher
A result in the prediabetes range means your blood sugar is running higher than normal but hasn’t crossed into diabetes territory. About 80% of people with prediabetes don’t know they have it, partly because there are no obvious symptoms at this stage. The good news is that prediabetes is often reversible with changes to diet, activity, and weight.
Targets If You Have Diabetes
Once you have a diabetes diagnosis, the goal shifts from “normal” to “well-managed.” The American Diabetes Association recommends most non-pregnant adults with diabetes aim for an A1c below 7%. That corresponds to an estimated average blood sugar of about 154 mg/dL.
Below 7% is a general guideline, not a universal rule. Some people can safely aim lower, closer to 6.5%, especially if they were diagnosed recently, are younger, and aren’t on medications that carry a risk of low blood sugar. Others benefit from a more relaxed target. The key tradeoff is this: lower A1c reduces the risk of long-term complications like nerve damage and kidney disease, but pushing too aggressively increases the chance of hypoglycemia, which can be dangerous on its own.
How A1c Translates to Daily Blood Sugar
If you also check blood sugar at home, it helps to know how A1c percentages map to the numbers you see on your meter. The conversion follows a straightforward formula, but a quick reference table is easier to use:
- 6% A1c: ~126 mg/dL average
- 6.5%: ~140 mg/dL
- 7%: ~154 mg/dL
- 8%: ~183 mg/dL
- 9%: ~212 mg/dL
- 10%: ~240 mg/dL
Keep in mind that A1c is an average. Two people can have the same A1c but very different daily patterns. One might have steady blood sugar hovering near 154 mg/dL, while the other swings between 80 and 250. Your A1c won’t reveal those swings, which is why daily monitoring still matters for people on insulin or medications that affect blood sugar.
Adjusted Targets for Older Adults
For older adults, guidelines are more lenient because the risks of low blood sugar become more serious with age. Falls, confusion, and heart rhythm problems from hypoglycemia can be life-threatening, and the long-term benefits of tight blood sugar control take years to materialize.
Healthy older adults with a life expectancy of more than 10 years generally aim for an A1c below 7.5%. For those with significant chronic conditions or a life expectancy under 10 years, a target of 8% or lower is reasonable. Frail older adults with severe health problems or cognitive impairment may be advised to stay below 8.5%, which translates to an average blood sugar around 200 mg/dL. At that level, the priority shifts toward avoiding dangerous highs and lows rather than chasing a perfect number.
Targets During Pregnancy
Pregnancy calls for tighter control. High blood sugar during the first trimester raises the risk of birth defects, while elevated levels later in pregnancy increase the chance of preeclampsia, preterm delivery, and the baby growing too large.
Before conception, the goal is an A1c below 6.5% to minimize the risk of congenital anomalies. During pregnancy itself, the ideal target drops to below 6%, as long as that can be achieved without frequent episodes of low blood sugar. If hypoglycemia becomes a problem, the target may be relaxed to below 7%. These are tight ranges, which is why pregnant women with diabetes typically monitor blood sugar multiple times a day and adjust treatment frequently.
When Results May Be Inaccurate
A1c measures sugar attached to hemoglobin, so anything that changes your hemoglobin or red blood cell turnover can skew the result. Iron-deficiency anemia, sickle cell trait, thalassemia, significant blood loss, recent blood transfusions, and chronic kidney disease can all push your A1c reading artificially higher or lower than your true average blood sugar.
If you have any of these conditions, your doctor may use alternative tests like fructosamine (which measures blood sugar over two to three weeks) or rely more heavily on daily glucose monitoring to get an accurate picture. A falsely reassuring A1c could delay a diagnosis, and a falsely elevated one could lead to unnecessary treatment, so it’s worth flagging these conditions if your doctor isn’t already aware.
How Often to Get Tested
If your blood sugar is well controlled and stable, testing twice a year is typically enough. If you’ve recently changed medications, aren’t meeting your target, or were just diagnosed, testing every three months gives faster feedback on whether your management plan is working. Since A1c reflects a rolling three-month average, testing more often than every 12 weeks won’t add useful information.
For people without diabetes who had a normal result, repeat testing every three years is the standard screening recommendation. If your result was in the prediabetes range, annual testing helps track whether you’re trending toward diabetes or moving back toward normal.