HbA1c Test: What It Measures and How to Read the Report
HbA1c shows your average blood sugar over roughly the last three months. That is what makes it more dependable than a single day’s reading.
If HbA1c appears on your report and means nothing to you — it is a measure of your average blood sugar over roughly the last three months.
What it measures
Some sugar in the blood attaches to haemoglobin. The higher the sugar, and the longer it stays high, the more attaches. Red blood cells live about three months, so the test reflects that span.
That is also why a day of fasting or skipping sweets cannot "improve" this particular report.
The ranges
| Category | HbA1c |
|---|---|
| Normal | Below 5.7% |
| Prediabetes | 5.7% – 6.4% |
| Diabetes | 6.5% and above |
Ranges vary slightly between laboratories, so always read the range printed on your own report.
Preparation
None in particular. You do not need to fast, and the sample can be taken at any time of day — which is the test’s main convenience.
How often should it be repeated?
- No diabetes and no risk factors — as your doctor advises, usually within an annual check
- Prediabetes — commonly every 6-12 months
- Diabetes that is well controlled — commonly every 6 months
- Control that is unsettled, or a recent change of medication — commonly every 3 months
The interval is your doctor’s call, because it depends on your situation.
When the test can mislead
HbA1c does not reflect the true picture in some situations — significant anaemia, a recent blood donation or transfusion, pregnancy, and certain haemoglobin conditions. That is why doctors often order an ordinary sugar test alongside it.
Frequently asked questions
Do I need to fast for HbA1c?+
No. The sample can be taken at any time of day, including after a meal.
Can a week of careful eating improve the result?+
No. It reflects roughly three months of average sugar, so a few days make almost no difference.
How does it differ from fasting sugar?+
Fasting sugar shows the level at that moment; HbA1c shows a three-month average. Doctors often read both.
Can anaemia affect the result?+
Yes. With significant anaemia or a recent transfusion, HbA1c does not reflect the true picture.