An A1c level of 6.5% or higher means diabetes. That’s the threshold used by the American Diabetes Association and confirmed in their 2025 Standards of Care. Below that number, there are two other categories worth knowing: an A1c between 5.7% and 6.4% falls in the prediabetes range, and anything below 5.7% is considered normal.
What the 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 about three months, the result reflects your average blood sugar over that period rather than a single moment in time. That’s what makes it different from a finger-stick glucose reading, which only captures what’s happening right now.
Here’s how the ranges break down:
- Normal: below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or higher
To put those percentages in more concrete terms, an A1c of 7% translates to an estimated average blood sugar of about 154 mg/dL. An A1c of 9% corresponds to roughly 212 mg/dL. The higher the percentage, the more sugar has been circulating in your blood over the past two to three months.
How Diabetes Is Actually Diagnosed
A single A1c result at or above 6.5% doesn’t always lock in a diagnosis on its own. Doctors typically want a second test to confirm the result, unless you already have obvious symptoms of high blood sugar like frequent urination, extreme thirst, or unexplained weight loss. That confirmatory test can be another A1c draw or a different type of blood sugar test entirely.
The two other common diagnostic tests measure blood sugar more directly. One is a fasting blood sugar test, where a result of 126 mg/dL or higher indicates diabetes. The other is an oral glucose tolerance test, where you drink a sugary solution and your blood sugar is checked two hours later. A reading of 200 mg/dL or above on that test also qualifies as diabetes. Any of these three tests can be used, and your doctor may choose one over another depending on your situation.
One practical advantage of the A1c test: you don’t need to fast beforehand. You can eat and drink normally before having your blood drawn, which makes scheduling easier.
When A1c Results Can Be Misleading
The A1c test isn’t perfectly accurate for everyone. Because it works by measuring sugar on hemoglobin (the protein in red blood cells that carries oxygen), anything that changes your hemoglobin or red blood cell turnover can skew the number.
Hemoglobin variants are the most significant factor. These are inherited differences in the structure of hemoglobin that are more common in people with ancestry from Africa, South and Southeast Asia, the Mediterranean, and parts of Central and South America. The most common variants that affect A1c accuracy include hemoglobin S (which causes sickle cell disease), hemoglobin C, and hemoglobin E. Depending on the variant and the lab method used, your A1c could read falsely high or falsely low.
A falsely high result might make it look like your blood sugar is worse than it really is, potentially leading to unnecessary treatment changes. A falsely low result is more dangerous in some ways, because it can mask poorly controlled blood sugar and create a false sense that everything is fine.
If you were born in the U.S. after 2006, you were likely screened for hemoglobin S at birth. But if you were born before then, you may not know whether you carry a variant. Your doctor might suspect one if your A1c result doesn’t match your glucose meter readings, if you have a family history of blood disorders, or if your family comes from a region where hemoglobin variants are common. In those cases, a direct blood sugar test may be more reliable for diagnosis.
What Prediabetes Means in Practice
An A1c between 5.7% and 6.4% places you in the prediabetes range. This isn’t a harmless in-between zone. It means your blood sugar is consistently higher than normal, and without changes, the progression to type 2 diabetes is likely. Roughly 70% of people with prediabetes eventually develop diabetes.
The useful thing about catching it at this stage is that prediabetes is often reversible. Modest weight loss (even 5% to 7% of body weight), regular physical activity, and dietary changes can bring A1c levels back below 5.7%. For someone who weighs 200 pounds, that’s a loss of 10 to 14 pounds. These changes don’t need to be dramatic to be effective, but they do need to be sustained.
A1c Targets After Diagnosis
Once you’ve been diagnosed with diabetes, the A1c test shifts from a diagnostic tool to a monitoring tool. Most adults with type 2 diabetes aim for an A1c below 7%, though your personal target may be slightly higher or lower depending on your age, how long you’ve had diabetes, and what other health conditions you have.
You’ll typically have your A1c checked two to four times per year. If your treatment plan changes or your levels aren’t at target, your doctor may test more frequently. Each result gives you a rolling three-month snapshot, so improvements from lifestyle changes or medication adjustments take at least that long to fully show up in the number. If you make a significant change today, expect to see the impact reflected at your next A1c test, not immediately.