A normal A1C level is below 5.7%. This number represents the percentage of your red blood cells that have glucose attached to them, averaged over roughly three months. Results between 5.7% and 6.4% fall into the prediabetes range, and 6.5% or higher indicates diabetes.
What the A1C Test Measures
Glucose in your bloodstream naturally sticks to hemoglobin, the protein inside red blood cells that carries oxygen. The more glucose circulating in your blood over time, the more hemoglobin gets coated. Since red blood cells live about three months before your body replaces them, the A1C test captures a rolling average of your blood sugar over that entire window. This makes it far more useful than a single finger-prick glucose reading, which only tells you what’s happening at one moment in time.
Unlike a fasting glucose test, an A1C draw doesn’t require you to skip meals beforehand. You can eat normally before the blood draw, which makes it a convenient screening tool during routine checkups.
Normal, Prediabetes, and Diabetes Ranges
The CDC uses these thresholds to classify results:
- Normal: below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or above
A result right at 5.7% doesn’t mean you suddenly have a blood sugar problem. The shift from normal to prediabetes is gradual, and the cutoffs represent points along a continuous spectrum where risk starts to climb meaningfully. Still, prediabetes is worth taking seriously. It signals that your body is beginning to struggle with processing glucose, and lifestyle changes at this stage can often prevent progression to type 2 diabetes.
What Your A1C Means in Everyday Blood Sugar
A1C percentages can feel abstract. Translating them into estimated average glucose (eAG) gives you a number closer to what you’d see on a glucose meter. The conversion formula is: multiply your A1C by 28.7, then subtract 46.7. That gives you an average daily blood sugar in mg/dL.
Some practical reference points:
- A1C of 6.0%: roughly 126 mg/dL average blood sugar
- A1C of 6.5%: roughly 140 mg/dL
- A1C of 7.0%: roughly 154 mg/dL
If your A1C is in the normal range, below 5.7%, your estimated average blood sugar is typically under 117 mg/dL. That’s the kind of number your body maintains comfortably when insulin is working the way it should.
A1C Targets for People With Diabetes
If you already have diabetes, “normal” shifts to a different conversation. The American Diabetes Association recommends a target of below 7% for most adults with diabetes, which corresponds to an average blood sugar of about 154 mg/dL. But the ADA is also clear that there’s no universal target. Your ideal number depends on your age, how long you’ve had diabetes, what other health conditions you’re managing, and your risk of low blood sugar episodes.
Older adults or people with a history of severe hypoglycemia may have a more relaxed target, sometimes 7.5% or 8%, because pushing too aggressively to lower A1C can cause dangerous blood sugar drops. Younger adults who were recently diagnosed and have no complications generally aim for something closer to normal. The point is that A1C management in diabetes is personalized, not one-size-fits-all.
When Results Can Be Misleading
Because the A1C test depends on red blood cells, anything that changes how long those cells survive or how they behave can skew results. Conditions that shorten red blood cell lifespan, like sickle cell disease or other hemoglobin variants, tend to produce falsely low A1C readings. Your blood sugar may actually be higher than the test suggests because the glucose-coated cells are being cleared too quickly.
Iron-deficiency anemia can push results in the opposite direction, making A1C appear falsely high. Significant blood loss, recent blood transfusions, and kidney disease can also interfere with accuracy. Pregnancy changes blood volume and red blood cell turnover enough that A1C becomes less reliable, particularly in the second and third trimesters. If any of these apply to you, your provider may rely more on direct glucose measurements instead.
Understanding Units Outside the US
If you’re reading lab results from outside the United States, your A1C may be reported in mmol/mol rather than a percentage. This is the international standard (IFCC units). The conversions for key thresholds look like this:
- 5.0% = 31 mmol/mol
- 6.0% = 42 mmol/mol
- 6.5% = 48 mmol/mol
- 7.0% = 53 mmol/mol
A normal result in IFCC units is below about 39 mmol/mol. The prediabetes range runs from 39 to 47 mmol/mol, and diabetes is diagnosed at 48 mmol/mol or above.
How to Lower a Borderline A1C
If your result lands in the prediabetes zone, the most effective tools are straightforward: regular physical activity and modest weight loss. Losing 5% to 7% of your body weight, roughly 10 to 14 pounds for someone weighing 200 pounds, has been shown to significantly reduce the risk of progressing to type 2 diabetes. That doesn’t require extreme dieting. Consistent changes like reducing refined carbohydrates, eating more fiber, and getting 150 minutes of moderate activity per week (walking counts) add up over time.
A1C responds to sustained habits, not quick fixes. Because the test reflects a three-month average, you won’t see meaningful changes until you’ve maintained new habits for at least that long. A recheck after three to six months gives a realistic picture of whether your changes are working.
How Often to Get Tested
For adults with no risk factors and a previous normal result, screening every three years is generally sufficient starting at age 35. If you have risk factors for type 2 diabetes, such as being overweight, having a family history, or belonging to a higher-risk ethnic group, screening may start earlier and happen more frequently. People with prediabetes typically get tested annually to track whether their numbers are stable, improving, or trending upward. Those managing diabetes usually have their A1C checked every three to six months, depending on how stable their blood sugar control is.