Diabetes · 4 min read
HbA1c: the 3-month sugar test, explained simply
Why doctors trust HbA1c more than a single fasting sugar, what the percentages mean, and how often to test.
By the TarragonHealth editorial team
What HbA1c actually measures
Sugar in your blood sticks to haemoglobin, the protein inside red blood cells. Because red cells live about three months, measuring how much sugar is stuck to them (HbA1c) reveals your average blood sugar over the past two to three months — not just this morning.
That is why a single fasting glucose can look fine on a good day while HbA1c tells the fuller story.
Reading your result
As a widely used guide: below 5.7% is in the normal range; 5.7–6.4% is called prediabetes — a warning zone where change still prevents diabetes; 6.5% or higher on a proper laboratory test supports a diagnosis of diabetes.
If you already live with diabetes, your doctor will set a personal target — often around 7% — balancing control against the risk of sugar going too low. Your target is a conversation, not a universal number.
How often should you test?
If you have diabetes, HbA1c every three to six months shows whether your plan is working. If you are in the prediabetes zone, a yearly test tracks which direction you are moving. If you have risk factors — family history, excess weight, previous high readings — ask about testing rather than waiting for symptoms.
The point of the number
HbA1c is not a grade on your character; it is feedback. Food, movement, medicines and stress all move it, and it responds within months. People bring it down every day — usually with a mix of small consistent changes and the right prescription, reviewed regularly.
This article is general health information, not medical advice, a diagnosis, or a treatment plan. Always talk to a doctor about your own situation — and if you feel seriously unwell, go to a hospital now.