An A1C between 5.7% and 6.4% is considered prediabetic. Below 5.7% is normal, and 6.5% or above crosses into the diabetes range. These thresholds, used by both the American Diabetes Association and the CDC, give your doctor a snapshot of how your blood sugar has been running over the past two to three months.
How the A1C Test Works
The test measures how much sugar has attached to hemoglobin, the protein inside red blood cells that carries oxygen. When blood sugar runs high, more glucose coats those cells. Since red blood cells live about three months, the percentage of sugar-coated hemoglobin reflects your average blood sugar over that entire window. That’s what makes it more useful than a single finger stick: it captures the big picture rather than one moment in time.
A result of 5.7% means roughly 5.7% of your hemoglobin is coated with glucose. The higher that number climbs within the 5.7% to 6.4% range, the greater your risk of eventually developing type 2 diabetes.
What Prediabetes Actually Means
Prediabetes isn’t a disease diagnosis. It’s a warning that your body is starting to struggle with blood sugar regulation, but hasn’t crossed the threshold into diabetes. Your cells are becoming less responsive to insulin, so glucose lingers in the bloodstream longer than it should. Most people with prediabetes feel completely normal and have no symptoms at all, which is why screening matters.
A fasting blood glucose test can also identify prediabetes. A fasting level between 100 and 125 mg/dL points to the same metabolic problem the A1C is picking up. Your doctor may use either test or both to confirm a result.
Who Should Get Screened
The U.S. Preventive Services Task Force recommends screening adults aged 35 to 70 who are overweight or obese. If you’re from a population with higher diabetes rates (Black, Hispanic/Latino, American Indian/Alaska Native, or Native Hawaiian/Pacific Islander), screening should start earlier. For Asian Americans, screening is recommended at a lower BMI threshold of 23 rather than the standard 25, because metabolic risk rises at a lower body weight in this group.
If your result comes back in the prediabetic range, expect your doctor to recheck it periodically to see whether your numbers are holding steady, improving, or trending upward.
How Likely Prediabetes Leads to Diabetes
The trajectory varies more than most people expect. A large pooled analysis of 19 studies published in The Lancet Global Health tracked what happened to people with prediabetes over five years. Among younger men, about 8% progressed to type 2 diabetes, while 38% reverted to normal blood sugar. Older men progressed at a higher rate (roughly 14%), and older women had the highest progression rate at about 16%.
The encouraging takeaway: in every age and sex group, a significant portion of people moved back to normal. Prediabetes is not a one-way road. More than half of younger men and about a third of older adults returned to healthy blood sugar levels within five years.
Ethnicity Can Affect Your A1C Reading
One important nuance: A1C levels aren’t perfectly comparable across all racial and ethnic groups. A meta-analysis in PLOS One found that Black individuals without diabetes had A1C values averaging about 0.26 percentage points higher than white individuals at the same blood sugar levels. Asian individuals averaged 0.24 points higher, and Latino individuals about 0.08 points higher. These differences appear to be biological, related to how glucose binds to hemoglobin, not to differences in actual blood sugar control.
This means a Black or Asian person could receive a prediabetes diagnosis at the same true blood sugar level where a white person’s A1C reads as normal. If you fall just above the 5.7% cutoff and belong to one of these groups, a fasting glucose test or an oral glucose tolerance test can provide a clearer picture of your actual metabolic health.
Lowering Your A1C From the Prediabetic Range
Lifestyle changes are the primary tool for reversing prediabetes, and they work. The combination that consistently moves the needle is modest weight loss (5% to 7% of body weight), regular physical activity, and dietary changes that reduce refined carbohydrates and added sugars. A structured six-month trial found that even a relatively simple intervention using an app with standardized dietary advice produced a 0.2% greater A1C reduction compared to no intervention, alongside about 6.6 pounds of additional weight loss.
That 0.2% may sound small, but in the narrow 5.7% to 6.4% prediabetic window, it can be the difference between trending toward diabetes and sliding back to normal. Physical activity helps independently of weight loss because working muscles pull glucose from the bloodstream without needing as much insulin. Even 150 minutes per week of brisk walking makes a measurable difference.
The changes don’t need to be dramatic. What matters is consistency over months, not perfection over days. People who maintain even moderate improvements in diet and activity are the ones most likely to show up in that “reverted to normal” group at the five-year mark.