A normal A1C is below 5.7%. If you don’t have diabetes, that’s the number you want to see. An A1C between 5.7% and 6.4% falls in the prediabetes range, and 6.5% or above is used to diagnose diabetes. If you already have diabetes, the goal for most adults is to keep A1C below 7%.
What A1C Actually Measures
A1C reflects your average blood sugar over the past two to three months. Glucose in your blood naturally attaches to hemoglobin, the protein inside red blood cells that carries oxygen. The higher your blood sugar has been, the more glucose gets stuck to your hemoglobin. Since red blood cells live for roughly 100 days (with a half-life around 50 days), the test captures a rolling average rather than a single moment in time. That’s what makes it more useful than a single finger-stick reading for understanding your overall blood sugar control.
The Three Diagnostic Ranges
The CDC uses these thresholds to classify A1C results:
- Below 5.7%: Normal. Your blood sugar regulation is working well.
- 5.7% to 6.4%: Prediabetes. Your blood sugar is higher than normal but not yet in the diabetes range. This is the window where lifestyle changes, like losing 5% to 7% of your body weight and increasing physical activity, can meaningfully lower your risk of progressing to type 2 diabetes.
- 6.5% or above: Diabetes. A result at or above this level on two separate tests confirms a diabetes diagnosis.
A1C Goals If You Have Diabetes
Diagnosis and treatment targets are different things. While 6.5% is the cutoff for diagnosing diabetes, the American Diabetes Association sets the treatment goal for most adults with diabetes at below 7%. That might seem counterintuitive, but getting below 7% significantly reduces the risk of complications affecting your eyes, kidneys, and nerves, while still being realistic enough that most people can sustain it without constant dangerous blood sugar lows.
Your personal target could be different. Your doctor might set a tighter goal (closer to 6.5%) if you’re younger, recently diagnosed, or managing your diabetes without medications that cause low blood sugar. A more relaxed target (7.5% or even 8%) might make sense if you’re older, have a long history of diabetes, or are prone to severe low blood sugar episodes. There is no single number that’s right for everyone.
For children and adolescents with type 1 diabetes, international guidelines recommend aiming for 7% or below. Kids using advanced technology like continuous glucose monitors and automated insulin pumps can often target 6.5% or below, provided they can reach it safely without it taking a toll on quality of life.
What Your A1C Means in Daily Blood Sugar Terms
A1C percentages can feel abstract. Converting to estimated average glucose (eAG) gives you a number that looks like what you’d see on a glucose meter. The conversion formula is: multiply your A1C by 28.7, then subtract 46.7. Here’s what that looks like in practice:
- A1C of 6%: average blood sugar around 126 mg/dL
- A1C of 6.5%: average around 140 mg/dL
- A1C of 7%: average around 154 mg/dL
- A1C of 8%: average around 183 mg/dL
- A1C of 9%: average around 212 mg/dL
- A1C of 10%: average around 240 mg/dL
So the difference between a “normal” A1C and the diabetes treatment target of 7% is roughly the difference between an average blood sugar of 126 and 154 mg/dL. Each percentage point on the A1C scale represents roughly a 29 mg/dL change in average blood sugar.
How Often to Get Tested
If you have diabetes and your blood sugar is well controlled with a stable treatment plan, testing every six months is typically enough. If your treatment has recently changed, or you’re not hitting your target, every three months makes more sense so you and your doctor can see whether adjustments are working. People going through rapid health changes or dealing with very high blood sugar may need testing even more frequently.
If you don’t have diabetes, A1C isn’t part of routine blood work for everyone. It’s most commonly ordered if you have risk factors like being overweight, having a family history of diabetes, or being over 45.
When A1C Results Can Be Misleading
A1C is reliable for most people, but certain conditions can push the number artificially high or low. Because the test depends on red blood cells having a normal lifespan, anything that changes how quickly your body cycles through red blood cells will affect the result.
Conditions that shorten red blood cell life, like hemolytic anemia or recovery from significant blood loss, will make your A1C look falsely low. Your actual average blood sugar could be higher than the number suggests. On the other hand, iron deficiency anemia is associated with falsely elevated A1C readings, meaning your blood sugar control might be better than it appears.
Inherited hemoglobin variants, which are more common in people of African, Mediterranean, and Southeast Asian descent, can also interfere with the test. If you carry sickle cell trait or other hemoglobin variants, your A1C may not accurately reflect your true blood sugar average. In these cases, your doctor may rely more heavily on direct glucose monitoring, like fasting blood sugar tests or continuous glucose monitors, to get an accurate picture.
Pregnancy adds another layer of complexity. A1C tends to read higher in late pregnancy even in women without diabetes, largely because pregnancy commonly causes iron deficiency. Pregnant women are usually monitored with more frequent glucose checks rather than relying on A1C alone.