A1C results fall into three main ranges: below 5.7% is normal, 5.7% to 6.4% indicates prediabetes, and 6.5% or higher means diabetes. These cutoffs are used for diagnosis, but if you’re already managing diabetes, your personal target number may be different from the diagnostic threshold.
The Three Diagnostic Ranges
The A1C test measures the percentage of your red blood cells that have sugar attached to them. Because red blood cells live for about two to three months, the result reflects your average blood sugar over that window rather than a single moment in time.
- Normal: below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or higher
These thresholds have remained consistent across the most recent American Diabetes Association guidelines. In the 2024 update, the ADA moved A1C to the top of its testing hierarchy, recognizing that it’s the test most commonly used in real-world practice for diagnosing both diabetes and prediabetes.
What A1C Translates to in Daily Blood Sugar
A1C percentages can feel abstract. A useful way to think about them is through estimated average glucose (eAG), which converts your A1C into the kind of number you’d see on a glucose meter. The formula is straightforward: multiply your A1C by 28.7, then subtract 46.7. That gives you your estimated average in mg/dL.
Here’s how some common A1C values translate:
- 6%: average blood sugar of about 126 mg/dL
- 6.5%: about 140 mg/dL
- 7%: about 154 mg/dL
- 8%: about 183 mg/dL
- 9%: about 212 mg/dL
- 10%: about 240 mg/dL
So the difference between an A1C of 7% and 8% represents roughly a 30 mg/dL jump in average blood sugar. That kind of context can help you understand what a small change in your A1C percentage actually means day to day.
Target Ranges for People With Diabetes
Diagnosis and management use different numbers. Getting diagnosed at 6.5% doesn’t mean 6.5% is your goal going forward. For most adults with diabetes, the standard target is below 7%. That corresponds to an average blood sugar of about 154 mg/dL and is associated with significantly lower rates of complications affecting the eyes, kidneys, and nerves.
But targets vary depending on your age, overall health, and risk of low blood sugar episodes (hypoglycemia). The ADA breaks it down this way for older adults:
- Healthy older adults with few other chronic conditions: below 7% to 7.5%
- Older adults with multiple chronic illnesses or mild cognitive impairment: below 8%
- Those in poor health or with significant cognitive decline: A1C targets become less useful, and the focus shifts to avoiding dangerously high or low blood sugar rather than hitting a specific number
The logic is simple. Tighter blood sugar control reduces long-term complications, but it also increases the risk of hypoglycemia. For someone with a long life expectancy and otherwise good health, the tradeoff favors tighter control. For someone who is frail or managing several serious conditions, a low blood sugar episode can be more immediately dangerous than a slightly elevated A1C.
A1C Targets During Pregnancy
Pregnancy calls for tighter glucose control because elevated blood sugar raises the risk of birth defects, preeclampsia, and preterm delivery. For women with preexisting diabetes who are planning a pregnancy, the recommended A1C is below 6.5% before conception.
Once pregnant, the ideal target drops further to below 6%, provided that level can be reached without frequent episodes of low blood sugar. If hypoglycemia becomes a problem, the target can be relaxed to below 7%. These goals are more aggressive than typical diabetes management because even moderately elevated blood sugar during pregnancy carries outsized risks for the developing baby.
When A1C Results Can Be Misleading
The A1C test measures sugar on hemoglobin, the oxygen-carrying protein in red blood cells. Anything that changes how long your red blood cells survive or alters your hemoglobin can throw off the result.
Sickle cell trait is one of the most common culprits. Depending on the lab method used, it can push results falsely high or falsely low. Other hemoglobin variants, including hemoglobin E trait, tend to produce artificially lower readings, meaning your actual blood sugar control is worse than the number suggests. Elevated fetal hemoglobin, which can occur in certain blood disorders, also interferes with some testing methods.
Conditions that affect red blood cell turnover, like iron-deficiency anemia or recent blood loss, can skew results too. If your red blood cells are being replaced faster than usual, they’ve had less time to accumulate sugar, and your A1C may read lower than your true average. The reverse happens when red blood cell turnover slows down.
If you have a known hemoglobin variant or a condition affecting your red blood cells, your provider may rely more on direct blood sugar monitoring or use an A1C testing method that isn’t affected by your specific variant.
How Often to Get Tested
If you have diabetes and your blood sugar is stable and on target, you’ll typically need an A1C test twice a year. If your numbers are above goal or you’ve recently changed your treatment plan, testing every three months gives a clearer picture of whether adjustments are working. Since the test reflects a two- to three-month average, checking more frequently than that won’t yield meaningful new information.
For people without diabetes, an A1C test is part of routine screening. If your result comes back in the prediabetes range (5.7% to 6.4%), yearly testing helps track whether your numbers are holding steady or creeping toward the diabetes threshold. A result in that range doesn’t make diabetes inevitable. Weight loss, regular physical activity, and dietary changes can slow or reverse the progression for many people.