The prediabetic A1c range is 5.7% to 6.4%. An A1c below 5.7% is considered normal, and an A1c of 6.5% or higher meets the threshold for type 2 diabetes. This range is used by both the American Diabetes Association and the CDC as the standard diagnostic criterion.
What the A1c Test Actually Measures
The A1c test reflects your average blood sugar level over the past two to three months. It works by measuring how much sugar has attached to hemoglobin, the protein in red blood cells that carries oxygen. Because red blood cells live for about three months, the test captures a rolling average rather than a single snapshot.
That’s what makes it different from a finger-stick glucose reading, which only tells you what your blood sugar is doing right now. A single high reading after a big meal doesn’t mean much on its own. An elevated A1c means your blood sugar has been running higher than normal consistently over weeks.
The Three A1c Categories
- Normal: below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or above
A result of 5.7% sits right at the border. Someone at the lower end of the prediabetic range (5.7% to 5.9%) has a different risk profile than someone at 6.3% or 6.4%, even though both technically fall under the same label. The closer your number is to 6.5%, the more urgently lifestyle changes matter.
Who Should Get Tested
The U.S. Preventive Services Task Force recommends screening for prediabetes and type 2 diabetes in adults aged 35 to 70 who are overweight or obese (a BMI of 25 or higher). For Asian Americans, screening is recommended at a lower BMI of 23 or higher because diabetes risk rises at a lower body weight in this population.
Earlier screening is also recommended for people from groups with disproportionately high diabetes rates, including American Indian/Alaska Native, Black, Hispanic/Latino, and Native Hawaiian/Pacific Islander communities. If you fall into one of these groups, it’s worth getting tested before age 35, especially if you carry extra weight around your midsection or have a family history of diabetes.
When A1c Results Can Be Misleading
The A1c test isn’t perfectly accurate for everyone. Because it depends on hemoglobin in red blood cells, anything that changes how long your red blood cells survive or how hemoglobin behaves can skew the result.
Iron deficiency anemia, which is common in women of reproductive age, tends to push A1c readings falsely higher. On the other hand, conditions that shorten the lifespan of red blood cells, like hemolytic anemia or significant recent blood loss, will make A1c appear falsely low. Chronic kidney disease, sickle cell trait, and pregnancy can also distort results. If you have any of these conditions, your doctor may use a different test to get an accurate picture of your blood sugar control.
Race also plays a role. Research from the CDC has found that Black individuals tend to have higher A1c levels than white individuals at the same average blood glucose. This means the standard 5.7% cutoff may flag prediabetes earlier in some populations than others. The optimal A1c cutoff for distinguishing prediabetes from normal blood sugar was 5.7% in Black participants versus 5.5% in white participants in one large analysis. These differences don’t change the official diagnostic ranges, but they’re worth understanding if your result lands right near a cutoff.
What Happens if You Stay in the Prediabetic Range
Prediabetes is not a guaranteed path to diabetes, but it’s not harmless either. Roughly 5% to 10% of people with prediabetes progress to type 2 diabetes each year. A large pooled analysis of 19 studies tracked what happened to people over five years: among younger men with prediabetes, about 8% developed type 2 diabetes, while 38% reverted to normal blood sugar levels. Among older men, 13.5% progressed to diabetes and 31% returned to normal. The rest stayed in the prediabetic range.
Those numbers highlight two important things. First, progression isn’t inevitable. A significant percentage of people with prediabetes return to normal without medication. Second, the risk is real and increases with age. The longer blood sugar stays elevated, the more strain it places on the cells in your pancreas that produce insulin.
How to Lower Your A1c
The most convincing evidence for reversing prediabetes comes from the Diabetes Prevention Program, a landmark study that tested structured lifestyle changes against medication. Participants who lost 5% to 7% of their body weight (10 to 14 pounds for someone weighing 200 pounds) and exercised at least 150 minutes per week reduced their risk of developing type 2 diabetes by 58%.
That 150 minutes per week works out to about 30 minutes of moderate activity, like brisk walking, five days a week. The weight loss component focused on reducing calories rather than any specific diet. The combination of modest weight loss and regular movement was more effective than medication in the study, particularly for people over 60, where the risk reduction was even higher.
If your A1c is at the higher end of the prediabetic range (6.0% to 6.4%), retesting every six to twelve months helps you track whether your changes are working. At the lower end, annual testing is typically sufficient.
Physical Signs of Insulin Resistance
Prediabetes itself rarely causes symptoms you can feel, which is why blood testing matters. But one visible clue is acanthosis nigricans: dark, velvety patches of skin that appear in body creases like the neck, armpits, or groin. These patches are a direct sign of insulin resistance and can show up before blood sugar levels rise enough to trigger a prediabetes diagnosis.
Not everyone with prediabetes develops these skin changes, and having them doesn’t confirm prediabetes on its own. But if you notice darkened, thickened skin in those areas, especially combined with other risk factors like excess weight or a family history of diabetes, it’s a reason to get your A1c checked.