A good A1C level is below 5.7%, which means your average blood sugar over the past two to three months has been in the normal range. Once A1C climbs above that number, it enters prediabetes territory, and at 6.5% or higher, it meets the threshold for diabetes. But “good” isn’t one-size-fits-all. Your ideal target depends on your age, health status, and whether you’re already managing diabetes.
What A1C Numbers Mean
The A1C test measures the percentage of your red blood cells that have sugar attached to them. Because red blood cells live for roughly 90 to 120 days, the test captures a rolling average of your blood sugar rather than a single snapshot. That makes it more useful than a fasting glucose reading for understanding long-term trends.
The standard diagnostic ranges break down like this:
- Below 5.7%: Normal blood sugar regulation
- 5.7% to 6.4%: Prediabetes
- 6.5% or higher: Diabetes
If you’ve been diagnosed with prediabetes, bringing your A1C back below 5.7% through diet, exercise, or weight loss is a realistic goal for many people and can delay or prevent a diabetes diagnosis.
A1C Targets If You Have Diabetes
For most adults and children with diabetes, the American Diabetes Association recommends an A1C of 7% or lower. That corresponds to an estimated average blood sugar of about 154 mg/dL. Staying at or below 7% significantly reduces the risk of damage to your eyes, kidneys, and nerves over time.
Not everyone should aim for 7%, though. Older adults, especially those dealing with frailty or multiple health conditions, often benefit from a higher target. For people with mild to moderate frailty, a range of 7% to 8% is considered appropriate. For those with severe frailty, 7.5% to 8.5% is more protective because pushing A1C too low in this group increases the risk of dangerous drops in blood sugar. In fact, an A1C below 7% in a frail older person may signal overtreatment.
If you’re pregnant or planning to become pregnant and have pre-existing diabetes, the targets are tighter. Most guidelines recommend an A1C of 6.5% or lower before conception, then below 6% during pregnancy to reduce the risk of complications for both parent and baby.
How A1C Translates to Daily Blood Sugar
A1C percentages can feel abstract. Converting them to estimated average glucose gives you a number you can compare to what you see on a home glucose meter. The relationship is straightforward: multiply your A1C by 28.7, then subtract 46.7.
- A1C of 6%: Average blood sugar around 126 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 full percentage point of A1C represents roughly a 29 mg/dL change in average blood sugar. So if your A1C drops from 8% to 7%, your average daily blood sugar has come down by about 29 mg/dL, which is a meaningful shift in how much sugar your blood vessels and organs are exposed to over time.
How Often to Test
Because the test reflects the lifespan of your red blood cells, retesting before three months have passed won’t give you an accurate picture of any changes you’ve made. If you’ve recently adjusted your diet, started a new medication, or changed your exercise habits, the full effect won’t show up until all the older red blood cells have been replaced, which takes about 90 days.
If your A1C is stable and you’re consistently meeting your target, testing every six months is generally enough. If your treatment has recently changed or your numbers aren’t where they need to be, testing every three months helps track progress without wasting a blood draw on results that haven’t had time to shift.
When A1C Results Can Be Misleading
Several common conditions can push your A1C reading higher or lower than your actual blood sugar control warrants. Knowing about these is important because acting on an inaccurate number could lead to unnecessary treatment changes.
Iron deficiency anemia tends to make A1C read falsely high. This is especially relevant during late pregnancy, when iron deficiency is common and can inflate the result even in someone without diabetes. Iron supplementation can bring the number back down to a more accurate level. On the other hand, any condition that shortens the life of your red blood cells, like hemolytic anemia or recovery from significant blood loss, will make A1C read falsely low because the sugar hasn’t had as long to accumulate on each cell.
Sickle cell trait, sickle cell disease, and other hemoglobin variants can interfere with the test in either direction depending on the lab method used. Chronic kidney failure, particularly in people on dialysis, also tends to make A1C unreliable as a marker. In these situations, your provider may rely on alternative tests or direct blood sugar monitoring instead. For frail older adults with conditions that interfere with A1C accuracy, keeping random blood sugar readings between 120 and 200 mg/dL throughout the day is a practical alternative target.
Lowering Your A1C
A1C responds to anything that brings your average blood sugar down over weeks and months. The most effective strategies vary depending on where you’re starting from.
If you’re in the prediabetes range (5.7% to 6.4%), lifestyle changes are the first line of action. Losing 5% to 7% of your body weight, getting at least 150 minutes of moderate activity per week, and reducing refined carbohydrates can bring A1C back to normal levels. These changes work because they improve how effectively your body uses insulin.
If you’re already managing diabetes with medication, A1C reflects how well your current regimen is working alongside your daily habits. Spikes after meals contribute heavily to A1C, so paying attention to carbohydrate portions at each meal, staying active after eating, and timing medication correctly all influence the number. Small, consistent changes tend to matter more than dramatic short-term efforts because A1C captures the full two-to-three-month average rather than your best or worst week.
A drop of even 1% in A1C is clinically significant. Going from 8% to 7% meaningfully reduces the long-term risk of complications affecting your eyes, kidneys, and nerves. The goal isn’t perfection on any given day. It’s a sustainable average that protects your health over years.