A normal A1c level is below 5.7%. This number represents the percentage of your red blood cells that have glucose attached to them, and it reflects your average blood sugar over roughly the past three months. An A1c between 5.7% and 6.4% falls in the prediabetes range, while 6.5% or higher indicates diabetes.
How the A1c Test Works
Hemoglobin is a protein inside your red blood cells that carries oxygen. When glucose circulates in your bloodstream, some of it naturally sticks to hemoglobin. The higher your blood sugar runs on a day-to-day basis, the more hemoglobin gets coated with glucose. Since red blood cells live about three months before your body replaces them, measuring how much glucose is stuck to your hemoglobin gives a reliable picture of your average blood sugar over that entire window.
This is what makes the A1c different from a finger-stick glucose reading, which only captures a single moment. A1c smooths out the daily ups and downs, so one high-sugar meal or a stressful morning won’t throw off the result. It’s a wider lens on your metabolic health.
The Three A1c Categories
- Normal: Below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or higher
These cutoffs, established by the American Diabetes Association and the National Institute of Diabetes and Digestive and Kidney Diseases, are the same for most adults. A result of 5.7% doesn’t mean you have diabetes, but it does signal that your blood sugar is running higher than ideal and that your risk of developing type 2 diabetes is elevated. Many people in the prediabetes range can bring their numbers back to normal through changes in diet, physical activity, and weight.
What Your A1c Translates to in Daily Blood Sugar
Lab reports sometimes include an “estimated average glucose” alongside your A1c percentage. This converts the A1c into the kind of number you’d see on a home glucose meter, measured in mg/dL. A 6% A1c corresponds to an estimated average blood sugar of about 126 mg/dL. At 7%, that average rises to roughly 154 mg/dL, and at 8% it’s around 183 mg/dL.
These conversions help you connect the abstract percentage to what’s actually happening in your bloodstream on a typical day. If your A1c is 5.4%, for example, your blood sugar has been averaging in a range most people would consider healthy. If it’s 6.2%, your daily average is creeping into territory where your body is starting to struggle with glucose regulation, even if you feel perfectly fine.
How Often You Should Get Tested
If your A1c comes back normal, there’s no firm consensus on the perfect retesting schedule. The U.S. Preventive Services Task Force suggests that screening every three years is a reasonable approach for adults with normal blood glucose levels. Your doctor may recommend testing sooner if you have risk factors like obesity, a family history of diabetes, or a history of gestational diabetes.
People already diagnosed with prediabetes or diabetes typically get tested more frequently, often every three to six months, to track whether their management plan is working.
When A1c Results Can Be Misleading
The test assumes your red blood cells have a normal lifespan and a typical form of hemoglobin. Several conditions can throw off the accuracy of your results, sometimes producing a number that’s higher or lower than your true average blood sugar.
Iron-deficiency anemia, chronic kidney disease, and heavy blood loss all alter how long your red blood cells survive, which changes how much glucose accumulates on them. If your red blood cells are turning over faster than usual, less glucose has time to attach, and your A1c may read falsely low. The reverse can happen too, giving a falsely high result.
Hemoglobin variants also matter. The most common form of hemoglobin is called hemoglobin A, but inherited variants exist that are more prevalent among people with ancestry from Africa, South and Southeast Asia, and the Mediterranean. These variants don’t increase your risk of diabetes, but depending on the lab method used, they can skew A1c results in either direction. A falsely high reading could lead to an unnecessary diagnosis or overly aggressive treatment, while a falsely low one might mask a real problem. If you know you carry a hemoglobin variant like sickle cell trait, your doctor may rely on alternative blood sugar tests instead.
A1c Targets for Older Adults
For people already managing diabetes, the goal A1c isn’t always the same across age groups. Older adults face a higher risk of hypoglycemia (dangerously low blood sugar) for several reasons: irregular eating patterns, declining kidney function, and medications like insulin that can overshoot. Cognitive decline, which is more common with age, also makes it harder to manage the daily demands of blood sugar monitoring and medication adjustments.
Because of these risks, A1c targets for older adults with diabetes are often set higher than the standard 6.5% threshold. A healthy older adult with few other chronic conditions may aim for an A1c below 7.0% to 7.5%. Someone managing multiple chronic illnesses or mild cognitive impairment may have a target below 8.0%. For those in poor health or with severe functional limitations, clinicians often move away from A1c targets altogether and focus instead on preventing episodes of very high or very low blood sugar.
A1c During Pregnancy
Pregnancy naturally lowers A1c readings because red blood cells turn over faster during this period. This happens in all pregnant people, whether or not they have diabetes. For those who do have diabetes during pregnancy, the ideal A1c goal is below 6% if it can be reached without causing low blood sugar episodes, though it may be relaxed to below 7% when needed.
A1c plays a secondary role during pregnancy overall. Daily glucose monitoring provides more actionable, real-time data for managing blood sugar. After delivery, A1c remains unreliable for a while. For women being screened for diabetes after a pregnancy with gestational diabetes, a glucose tolerance test is preferred over A1c at 4 to 12 weeks postpartum, since the effects of increased red blood cell turnover and blood loss during delivery can still suppress the reading.