An A1C between 5.7% and 6.4% is considered prediabetic. This range, established by the American Diabetes Association’s 2025 standards of care and used by the CDC, means your average blood sugar over the past two to three months has been higher than normal but not yet high enough to qualify as type 2 diabetes (6.5% or above).
What A1C Actually Measures
A1C reflects the percentage of your red blood cells that have sugar permanently attached to them. Because red blood cells live for about three months, the test captures a rolling average of your blood sugar rather than a single snapshot. A result of 5.7% means roughly 5.7% of your hemoglobin (the oxygen-carrying protein in red blood cells) has been coated with glucose. The higher your blood sugar runs day to day, the more coating builds up.
This is different from a fasting blood sugar test, which only tells you what your glucose is doing on one particular morning. A fasting result of 100 to 125 mg/dL also qualifies as prediabetes, and your doctor may use either test or both. A third option, the oral glucose tolerance test, checks how your body handles a sugary drink over two hours. A two-hour reading of 140 to 199 mg/dL falls in the prediabetic range. You can meet the criteria on any one of these three tests.
When You Should Get Tested
The U.S. Preventive Services Task Force recommends screening for prediabetes and type 2 diabetes starting at age 35 for adults who are overweight or obese (BMI of 25 or higher). This threshold was recently lowered from 40. If you’re Asian American, screening is recommended at a BMI of 23 or higher because diabetes risk rises at a lower body weight in this population. People who are American Indian, Alaska Native, Black, Hispanic, Latino, or Native Hawaiian/Pacific Islander should also consider screening earlier than 35, since these groups face a disproportionately high prevalence of diabetes.
Factors That Can Skew Your Results
A1C is reliable for most people, but certain conditions can push the number higher or lower than your actual blood sugar warrants. Iron-deficiency anemia, chronic kidney disease, heavy bleeding, and anything that shortens or lengthens the lifespan of your red blood cells can distort the result. If you have a hemoglobin variant such as sickle cell trait, the test may read falsely high or falsely low depending on the lab method used. For people with sickle cell disease (HbSS, HbCC, or HbSC), the A1C test is considered unreliable and shouldn’t be used at all. In those cases, doctors rely on fasting glucose or the oral glucose tolerance test instead.
Ethnicity also plays a role that isn’t fully explained by blood sugar levels alone. Research from the Diabetes Prevention Program and other large studies has consistently found that Black, Hispanic, American Indian, and Asian adults have higher A1C readings than white adults even after accounting for identical fasting glucose, body weight, insulin resistance, and other variables. In one analysis, the adjusted A1C was 5.8% in white participants but 6.2% in Black participants and 6.0% in Asian participants, all with the same underlying glucose levels. This means a Black person could cross the 5.7% prediabetes threshold while having the same actual blood sugar as a white person who tests at 5.4%. It’s an imperfect cutoff, and it’s worth knowing if your result lands right at the border.
What Prediabetes Does to Your Body
Prediabetes is often described as a warning stage, but it isn’t entirely harmless while you’re in it. A study of 268 prediabetic adults found that 10.1% already had early signs of kidney damage (detected as excess protein in the urine), 7.8% had peripheral neuropathy (nerve damage causing numbness or tingling in the feet and hands), and 4.1% showed signs of retinopathy (damage to the small blood vessels in the eye). These are complications most people associate only with full diabetes, yet they can begin before you ever cross the 6.5% line.
The risk of progressing from prediabetes to type 2 diabetes is roughly 5 to 10% per year without intervention. Over a lifetime, the American Diabetes Association estimates that up to 70% of people with prediabetes will eventually develop type 2 diabetes. The closer your A1C sits to 6.4%, the faster that progression tends to happen.
How to Lower Your A1C
The most convincing evidence for reversing prediabetes comes from the Diabetes Prevention Program, a landmark trial that tested whether lifestyle changes could outperform medication. The two targets were straightforward: lose 7% of your starting body weight and get at least 150 minutes per week of moderate physical activity, roughly equivalent to brisk walking for about 20 minutes a day. Participants who hit these goals cut their risk of developing type 2 diabetes by 58%, which was significantly more effective than the medication group.
Seven percent of body weight is about 14 pounds for someone who weighs 200 pounds, or 17.5 pounds at 250. The study didn’t require extreme dieting or intense exercise. Walking was the most common activity, and the calorie reductions were modest. The key was consistency over time. Because A1C reflects a three-month average, you can typically see your number start to drop within one testing cycle if you make sustained changes. Many people with an A1C of 5.7% to 6.0% can return to a normal range (below 5.7%) with weight loss and regular movement alone.
If your A1C is closer to 6.4%, the path back may be longer, and your doctor may discuss whether medication could help alongside lifestyle changes. But the core strategy remains the same: reduce your average blood sugar enough that fewer of your red blood cells get coated with glucose over the next three months, and the number comes down.