A good A1C level is below 5.7%, which indicates normal blood sugar control over the past two to three months. If you have diabetes, the general target shifts to below 7%, though your ideal number depends on your age, overall health, and risk of low blood sugar episodes.
What A1C Actually Measures
Glucose in your bloodstream naturally sticks to hemoglobin, the protein inside red blood cells that carries oxygen. The more sugar in your blood over time, the more hemoglobin gets coated. An A1C test measures the percentage of your red blood cells carrying this sugar coating. Because red blood cells live about three months, the test captures your average blood sugar over that window rather than a single snapshot.
This makes A1C a useful complement to daily glucose checks. A finger-prick test tells you what’s happening right now. A1C tells you how things have been going overall.
The Three A1C Ranges
Diagnostic categories break down cleanly:
- 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 elevated but hasn’t crossed the diabetes threshold. This is the stage where lifestyle changes, including diet, exercise, and weight loss, are most effective at preventing progression. About one in three American adults falls into this category, and many don’t know it.
Any A1C result used to diagnose diabetes requires confirmation with a second test, unless you already have obvious symptoms like excessive thirst, frequent urination, or unexplained weight loss.
A1C Targets if You Have Diabetes
For most non-pregnant adults with diabetes, the American Diabetes Association recommends an A1C below 7%. That number corresponds to an estimated average blood sugar of about 154 mg/dL. Reaching this target significantly lowers the risk of complications affecting your eyes, kidneys, and nerves.
Some people can safely aim lower. If you can keep your A1C below 7% without frequent episodes of low blood sugar (hypoglycemia), a tighter target like 6.5% may offer additional benefit. The key word is “safely.” Pushing too aggressively with medication to chase a lower number can cause dangerous blood sugar drops, especially overnight or during physical activity.
On the other end, a less strict target of below 8% is sometimes more appropriate. This applies if you’ve had severe or frequent low blood sugar episodes, if you have other serious health conditions, or if the burden of treatment outweighs the benefit. Your target should reflect your individual situation, not a one-size-fits-all benchmark.
How A1C Targets Change With Age
For older adults, A1C goals are adjusted based on overall health, cognitive function, and how independently someone can manage daily activities. Healthy older adults with few other medical issues typically aim for below 7% to 7.5%. Those managing multiple chronic conditions or mild cognitive impairment have a reasonable goal of below 8%, with an emphasis on avoiding hypoglycemia rather than hitting the lowest possible number.
For older adults in poor health or with moderate to severe cognitive impairment, clinicians often move away from A1C targets entirely. The priority shifts to preventing symptoms from both high and low blood sugar rather than optimizing a lab number.
A1C During Pregnancy
Pregnancy calls for tighter control. Before conception, an A1C below 6.5% is recommended to reduce the risk of birth defects, preeclampsia, and other complications. During the second and third trimesters, the ideal target drops further to below 6%, which is associated with the lowest risk of delivering a large baby, preterm birth, and preeclampsia. If reaching that level would cause frequent low blood sugar, the goal can be relaxed to below 7%.
One important caveat: A1C naturally falls during pregnancy because red blood cell turnover increases. It also doesn’t capture the post-meal blood sugar spikes that most directly affect fetal growth. For these reasons, daily glucose monitoring is the primary tool during pregnancy, with A1C serving as a secondary check.
What Your A1C Means in Everyday Numbers
A1C percentages can feel abstract. Converting them to estimated average glucose (eAG) gives you a number that looks more like what you’d see on a glucose meter. The formula is straightforward: multiply your A1C by 28.7, then subtract 46.7.
- A1C of 6%: average blood sugar around 126 mg/dL
- A1C of 6.5%: about 140 mg/dL
- A1C of 7%: about 154 mg/dL
- A1C of 8%: about 183 mg/dL
- A1C of 9%: about 212 mg/dL
- A1C of 10%: about 240 mg/dL
Each 1% change in A1C reflects roughly a 29 mg/dL shift in your average blood sugar. That can help you gauge how much your daily numbers need to move to shift your A1C by a meaningful amount.
When the Test Can Be Misleading
A1C is reliable for most people, but certain conditions can skew results in either direction. Anything that shortens red blood cell lifespan, like hemolytic anemia or recent significant blood loss, means your red blood cells haven’t been around long enough to accumulate the usual amount of sugar. This produces a falsely low A1C that makes blood sugar control look better than it actually is.
Iron deficiency anemia pushes results the other direction, producing a falsely high reading. Kidney disease complicates things further through multiple mechanisms, including a type of chemical modification to hemoglobin and the anemia that often accompanies it. For people on dialysis, A1C tends to underestimate true blood sugar levels.
Genetic hemoglobin variants, which are more common in people of African, Mediterranean, and Southeast Asian descent, can also interfere with certain A1C testing methods. If your A1C doesn’t match what your daily glucose readings suggest, these conditions are worth discussing with your provider. Alternative tests that measure blood sugar over a shorter window, typically two to three weeks, can fill the gap.
How Often to Get Tested
If you have diabetes and you’re meeting your blood sugar goals on a stable treatment plan, testing every six months is sufficient. If your treatment has recently changed, or you’re not hitting your targets, every three months gives you faster feedback on whether adjustments are working. For people without diabetes, A1C is commonly checked as part of routine screening, especially after age 45 or if you have risk factors like obesity, family history, or a sedentary lifestyle.