What is a normal A1c for someone without diabetes?
The ranges
| A1c | Category | Approx. average glucose |
|---|---|---|
| Below 5.7% | Normal | Below 117 mg/dL (6.5 mmol/L) |
| 5.7–6.4% | Prediabetes | 117–137 mg/dL (6.5–7.6 mmol/L) |
| 6.5% or above | Diabetes | 140 mg/dL (7.8 mmol/L) or above |
Diagnosis normally requires two abnormal results, either two separate tests or two different tests from the same blood draw.
What the test actually measures
A1c measures the proportion of your hemoglobin that has glucose chemically attached to it. Because red blood cells live around three months, it acts as a rolling average of that period.
Two practical advantages: no fasting required, and no single bad morning can distort it. That makes it more convenient and more stable than a one-off glucose reading.
Its blind spots
It cannot show variability. A flat 154 mg/dL all day and a sawtooth swinging between 60 and 250 both produce an A1c around 7%. The second is considerably more dangerous, and the A1c cannot tell you which one you have. This is why continuous glucose monitoring reports "time in range" alongside the average.
It is unreliable in several conditions, because it depends on red cells surviving the full three months:
- Anemia, especially iron-deficiency or hemolytic
- Recent blood loss or transfusion
- Chronic kidney disease
- Pregnancy
- Sickle cell trait and other hemoglobin variants
- Recent erythropoietin treatment
In those situations fructosamine, a glucose tolerance test, or continuous monitoring may be used instead. If your A1c and your home readings persistently disagree, that mismatch is worth raising rather than assuming one of them is simply wrong.
Where "normal" is not the whole story
An A1c of 5.6% is technically normal and 5.7% is technically prediabetes, but nothing biological changes across that line. Someone at 5.6% who was 5.2% three years ago is on a trajectory worth attending to, even though both readings sit in the normal band.
Trend beats threshold. If you have had several A1c tests, look at the direction as well as the current value.
Last reviewed