A good A1C number for most people is below 5.7%, which indicates normal blood sugar control over the previous two to three months. If you already have diabetes, the general target shifts to 7% or less, though your specific goal depends on your age, health, and other factors.
What the A1C Ranges Mean
The A1C test measures the percentage of your red blood cells that have sugar attached to them. Because red blood cells live for about three months, the test captures your average blood sugar over that window rather than a single snapshot.
The three key ranges are straightforward:
- Below 5.7%: Normal. Your blood sugar has been well-controlled.
- 5.7% to 6.4%: Prediabetes. Blood sugar is elevated but not yet in the diabetes range.
- 6.5% or higher: Diabetes. Two separate tests at or above this level confirm a diagnosis.
These cutoffs matter because the jump from prediabetes to diabetes isn’t just a label change. It signals a meaningful increase in risk for heart disease, nerve damage, kidney problems, and vision loss. Catching yourself in the prediabetes range gives you a window where lifestyle changes (losing 5% to 7% of body weight, regular physical activity) can often bring numbers back down.
What Your A1C Translates to in Daily Blood Sugar
A1C percentages can feel abstract. What helps is converting them to estimated average glucose, the number you’d see on a blood sugar meter measured in mg/dL. Here’s how the two line up:
- A1C of 6%: average blood sugar around 126 mg/dL
- A1C of 6.5%: around 140 mg/dL
- A1C of 7%: around 154 mg/dL
- A1C of 8%: around 183 mg/dL
- A1C of 9%: around 212 mg/dL
- A1C of 10%: around 240 mg/dL
Each full percentage point of A1C corresponds to roughly a 28 to 29 mg/dL increase in average blood sugar. So if your doctor says your A1C dropped from 8% to 7%, that represents an average daily reduction of about 29 mg/dL, a change that significantly lowers your risk of complications over time.
Targets for People With Diabetes
The CDC recommends an A1C goal of 7% or less for most adults with diabetes. That 7% threshold has strong evidence behind it: staying at or below it substantially reduces the risk of eye, kidney, and nerve damage. But “most adults” is doing a lot of work in that sentence, because the right target varies.
For younger, otherwise healthy people with a recent diabetes diagnosis, some clinicians aim tighter, closer to 6.5%, as long as it doesn’t cause frequent low blood sugar episodes. The logic is simple: these patients have decades ahead, and tighter control early pays dividends later.
For older adults (roughly 65 and above) without major health problems, guidelines from multiple international diabetes organizations suggest a range of 7.0% to 7.5%. For frail or dependent older adults with multiple chronic conditions and a high risk of dangerous low blood sugar, the recommended range relaxes further to 7.6% to 8.5%. At that stage, avoiding the immediate danger of blood sugar crashes matters more than squeezing out marginally better long-term numbers.
A1C Targets During Pregnancy
Pregnancy tightens the goalposts. Women with preexisting diabetes are generally advised to get their A1C below 6.5% before conceiving, as long as doing so doesn’t trigger problematic low blood sugar. Every step closer to that target lowers the risk of complications for the baby, including excessive birth weight and birth defects.
An A1C above 10% is considered high risk enough that medical teams typically advise delaying pregnancy until it comes down. This isn’t a permanent barrier, just a signal that blood sugar needs closer management first.
When Your A1C Might Not Be Accurate
The A1C test is reliable for most people, but certain conditions can skew the results in ways worth knowing about.
Anything that shortens the lifespan of your red blood cells will make your A1C read falsely low. This includes recovering from significant blood loss and hemolytic anemia (where red blood cells break down faster than normal). The test measures sugar buildup on red blood cells over time, so if those cells are younger on average, they’ve had less time to accumulate sugar.
Iron deficiency anemia pushes things in the opposite direction, causing a falsely high A1C. This is especially relevant during late pregnancy, when iron deficiency is common and can inflate results in women who don’t even have diabetes. Iron supplementation tends to bring the A1C reading back in line.
Sickle cell disease and sickle cell trait also affect accuracy. The altered hemoglobin in these conditions can interfere with how the test is measured, and the associated anemia and red cell turnover further complicate interpretation. If you carry sickle cell trait or have sickle cell disease, your doctor may rely on alternative tests like fructosamine or glycated albumin for a more accurate picture.
Chronic kidney disease, particularly in patients on dialysis, tends to make A1C underestimate true blood sugar levels. The combination of anemia, certain medications, and chemical changes to hemoglobin in kidney failure all muddy the reading.
How Often to Get Tested
Testing frequency depends on where you stand. If you have prediabetes, once a year is typical. If you have diabetes that’s well-controlled without insulin, twice a year is generally enough. You’ll need more frequent testing, sometimes every three months, if you use insulin, recently changed medications, or are having trouble staying within your target range.
Because the test reflects a two-to-three-month average, testing more often than every three months rarely adds useful information. Your most recent weeks of blood sugar weigh more heavily in the result than the earlier weeks, so a test taken too soon after a medication change may not fully capture its effect.