An optimal A1C level for most people without diabetes is below 5.7%, which translates to an estimated average blood sugar of roughly 117 mg/dL or less over the previous two to three months. For people managing diabetes, the picture gets more nuanced. The “optimal” number shifts depending on your age, health status, pregnancy, and how safely you can reach a lower target without your blood sugar dropping too low.
What A1C Actually Measures
A1C reflects the percentage of your hemoglobin (the oxygen-carrying protein in red blood cells) that has glucose attached to it. Because red blood cells live about 90 to 120 days, the test captures a rolling average of your blood sugar over roughly the past two to three months rather than a single snapshot. A higher percentage means more sugar has been circulating in your blood during that window.
To put the numbers in practical terms, here’s what common A1C levels translate to in daily average blood sugar:
- 6% A1C: ~126 mg/dL average
- 7% A1C: ~154 mg/dL average
- 8% A1C: ~183 mg/dL average
- 9% A1C: ~212 mg/dL average
Standard Diagnostic Ranges
The CDC uses three tiers to interpret A1C results:
- Normal: below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or above
These cut-offs are diagnostic, meaning they’re used to identify whether you have a blood sugar problem in the first place. They’re separate from the treatment targets someone with diabetes would aim for.
Optimal Targets If You Have Diabetes
For most non-pregnant adults with diabetes, the American Diabetes Association recommends an A1C below 7%. That goal balances long-term protection against complications with the real-world risk of hypoglycemia, the potentially dangerous drops in blood sugar that can come from aggressive treatment.
Going lower than 7% is considered acceptable, and even beneficial, if you can get there safely without frequent low blood sugar episodes or medication side effects. Some people with type 2 diabetes who manage their condition through diet and exercise alone, or with medications that carry a low hypoglycemia risk, can comfortably maintain an A1C in the 6% range. The key word is “safely.” Pushing too hard toward a lower number with insulin or certain other medications can cause dangerous lows, especially overnight or during physical activity.
On the other end, a less stringent target of below 8% is appropriate for people with limited life expectancy or conditions where the risks of intensive treatment outweigh the benefits.
How Age and Health Status Shift the Target
For older adults, the ADA’s 2025 guidelines break targets into three categories based on overall health rather than age alone. Healthy older adults with few chronic conditions and intact cognitive function should aim for an A1C between 7.0% and 7.5%. Older adults with multiple chronic illnesses, mild cognitive impairment, or difficulty with daily tasks have a more relaxed target of below 8.0%. For those in poor health, with significant cognitive decline, or receiving end-of-life care, strict A1C targets are abandoned entirely. The focus shifts to simply avoiding blood sugar extremes: no dangerous lows and no levels high enough to cause symptoms like excessive thirst, frequent urination, or blurred vision.
The reasoning is straightforward. The benefits of tight blood sugar control accumulate over years and decades. Someone with a shorter life expectancy or fragile health is more likely to be harmed by a hypoglycemic episode than helped by a marginally lower A1C.
Targets During Pregnancy
Pregnancy demands tighter control. For women with preexisting diabetes planning a pregnancy, the goal is an A1C below 6.5% before conception to reduce the risk of birth defects, preeclampsia, and preterm delivery. Once pregnant, the ideal target drops to below 6% if it can be reached without significant hypoglycemia, though below 7% is acceptable when tighter control isn’t safe.
There’s an important caveat: A1C becomes a less reliable marker during pregnancy. Normal physiological changes speed up red blood cell turnover, which can artificially lower A1C readings. For this reason, direct blood sugar monitoring (fasting and after meals) is the primary tool for managing glucose in pregnancy, with A1C used as a secondary check. For gestational diabetes specifically, management relies almost entirely on glucose monitoring rather than A1C targets.
Why Even Prediabetic Levels Matter
A large Canadian study tracking over 600,000 adults without diabetes found that cardiovascular risk starts climbing well before A1C reaches the diabetic threshold of 6.5%. Men with A1C levels between 6.0% and 6.4% (the upper end of prediabetes) had a 38% higher risk of cardiovascular hospitalization compared to those with A1C between 5.0% and 5.4%. Women in the same range had a 17% higher risk. At 6.5% and above, the risk jumped to 79% higher for men and 51% higher for women.
Interestingly, even the 5.5% to 5.9% range showed a 12% increased risk in men, though not in women. This suggests that for cardiovascular health, an A1C in the low 5% range is genuinely optimal, not just “normal.” It also means that a prediabetes diagnosis isn’t a waiting room before diabetes. It’s a signal that your cardiovascular risk is already elevated.
When A1C Results Can Be Misleading
Several conditions can make your A1C reading inaccurate, which matters if you’re using it to guide treatment decisions. Iron deficiency anemia tends to push A1C readings falsely high. Correcting the iron deficiency with supplements lowers A1C even without any change in actual blood sugar. Conditions that shorten red blood cell lifespan, like hemolytic anemia or recovery from significant blood loss, pull A1C readings falsely low because the red blood cells haven’t been around long enough to accumulate glucose.
Hemoglobin variants, including sickle cell trait and hemoglobin C trait, can interfere with certain testing methods and produce unreliable results. Chronic kidney disease, particularly in people on dialysis, also tends to make A1C underestimate true blood sugar levels. If any of these apply to you, alternative markers like fructosamine or glycated albumin, or continuous glucose monitoring, may give a more accurate picture.
Children and Adolescents With Type 2 Diabetes
The 2025 guidelines introduced a tighter A1C goal for most children and adolescents with type 2 diabetes: below 6.5%, down from the previous 7% threshold used for adults. This reflects the fact that younger people face decades of potential exposure to elevated blood sugar and typically use medications with a low risk of hypoglycemia, making a more ambitious target both safer and more impactful over a lifetime.