An A1C between 5.7% and 6.4% is considered prediabetic. Below 5.7% is normal, and 6.5% or higher on two separate tests indicates type 2 diabetes. This single blood test gives you a snapshot of your average blood sugar over the past three months, making it one of the most practical tools for catching blood sugar problems early.
What the A1C Test Actually Measures
Glucose in your blood naturally sticks to hemoglobin, the protein inside red blood cells that carries oxygen. The more sugar circulating in your blood over time, the more hemoglobin gets coated with it. An A1C test measures the percentage of your red blood cells carrying this sugar coating.
The reason it reflects roughly three months of blood sugar history is straightforward: red blood cells live about three months. So the sugar accumulated on those cells is a running record of your blood glucose levels during their lifespan. Unlike a fasting blood sugar test, which captures a single moment, the A1C doesn’t require fasting and isn’t thrown off by what you ate the night before.
The Prediabetes Range, Broken Down
The 5.7% to 6.4% range covers a wide spectrum. Someone at 5.7% is at the earliest stage of blood sugar dysregulation, while someone at 6.4% is one tick away from a diabetes diagnosis. Your position within that range matters for understanding your personal risk and how aggressively you may want to pursue lifestyle changes.
There’s no official “low prediabetes” versus “high prediabetes” classification, but in practice, doctors often pay closer attention when A1C creeps above 6.0%. At that point, your average blood sugar is high enough that the progression toward diabetes becomes more likely without intervention.
What Prediabetes Means for Your Future Risk
A prediabetes diagnosis doesn’t guarantee you’ll develop type 2 diabetes, but the lifetime odds are significant. Research published in BMJ Open Diabetes Research & Care found that a 45-year-old woman with prediabetes has roughly a 57% lifetime risk of progressing to diabetes, while a 45-year-old man has about a 46% lifetime risk. The 10-year risk at that same age is lower, around 9% to 14%, which means progression tends to happen gradually over decades rather than all at once.
The annual conversion rate is roughly 2 to 4 out of every 100 people with prediabetes developing diabetes in a given year. That slow pace is actually good news: it means there’s a meaningful window to change course.
Prediabetes Can Be Reversed
The strongest evidence for reversing prediabetes comes from the Diabetes Prevention Program, a landmark study that the CDC still uses as the foundation for its national lifestyle change program. Participants who lost 5% to 7% of their body weight (roughly 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%. For people over 60, the reduction was even more dramatic: 71%.
These weren’t extreme interventions. The exercise target works out to about 30 minutes of brisk walking five days a week. The weight loss goal is modest by most standards. Even 15 years later, participants who made these changes still had a 27% lower incidence of diabetes compared to the control group, suggesting the benefits are durable even if some weight is regained over time.
When A1C Results Can Be Misleading
The A1C test is reliable for most people, but certain conditions can push results artificially high or low. Severe anemia, kidney failure, liver disease, and blood disorders like sickle cell anemia or thalassemia all interfere with how hemoglobin behaves, which distorts the reading. Certain medications, including opioids and some HIV drugs, can also skew results. Blood loss, recent transfusions, and pregnancy (especially early or late stages) are other known factors.
If any of these apply to you, your doctor will likely confirm results with an alternative test. The two most common are a fasting blood sugar test, where prediabetes is defined as 100 to 125 mg/dL, and a glucose tolerance test, where a reading of 140 to 199 mg/dL two hours after drinking a sugary solution indicates prediabetes. These tests measure blood sugar differently than A1C and can provide a clearer picture when A1C alone isn’t trustworthy.
What to Do With a Prediabetic A1C
If your A1C comes back between 5.7% and 6.4%, the most useful thing to know is that this is one of the most reversible stages of metabolic disease. Your body is still producing insulin and responding to it, just not as efficiently as it should. The cellular machinery isn’t broken yet, which is why relatively modest changes in weight, diet, and activity level can bring your numbers back to normal.
Retesting typically happens every 6 to 12 months, depending on where you fall in the range and what other risk factors you have. If your A1C is trending downward over two or three tests, that’s a strong signal that whatever you’re doing is working. If it’s holding steady or climbing, that’s a signal to adjust your approach before you cross the 6.5% threshold.