If you or someone you love lives with diabetes, you have probably heard the word HbA1c (pronounced “H-B-A-one-C”). It is one of the most common blood tests in diabetes care, yet many people leave appointments unsure what the number actually means. This guide explains it in plain language.
The short answer
HbA1c is a blood test that shows your average blood glucose over the past two to three months. Where a finger-prick or sensor reading is a snapshot of one moment, HbA1c is more like a long-exposure photograph.
How does it work?
Glucose in the blood sticks to haemoglobin, the protein in red blood cells that carries oxygen. The more glucose in your blood, the more haemoglobin becomes “glycated”. Red blood cells live for about three months, so the test reflects roughly that period. It is usually taken as a blood sample at a clinic or laboratory, and some clinics use a quick finger-prick device.
What do the numbers look like?
HbA1c can be reported in two ways: as a percentage (for example, 7.0%) or in mmol/mol (for example, 53 mmol/mol). Different countries use different units, so check which one your results use. Health authorities commonly use 6.5% (48 mmol/mol) or above as one of the criteria for diagnosing diabetes, but a diagnosis is made by a healthcare professional, usually with repeat testing.
What is a “good” HbA1c?
This is the most important point: your target is personal. It depends on your age, your type of diabetes, your treatment, other health conditions, and your risk of low blood glucose. A target that is right for one person may not be right for another, so ask your care team what range is right for you.
Why does it matter?
Over many years, higher average glucose is linked with a higher risk of problems affecting the eyes, kidneys, nerves, feet and heart. Regular HbA1c checks help you and your team see whether your plan is working and whether it needs adjusting. How often you are tested will depend on your situation.
When might HbA1c be misleading?
HbA1c is a useful tool, but it is not perfect. Anaemia, some inherited haemoglobin variants, recent blood loss or transfusion, pregnancy and kidney disease can all affect the result. It also hides the ups and downs: two people can have the same HbA1c with very different daily patterns. That is why many people also use finger-pricks or sensors.
Questions to ask at your next appointment
- What was my last HbA1c, and what is my target?
- Is my HbA1c moving in the right direction?
- Could anything be affecting the accuracy of my result?
- Do my day-to-day readings match my HbA1c?
- What one change would make the biggest difference for me?
A final word
A number is not a verdict on you. HbA1c is simply information, to be used with your care team to make decisions that fit your life. If the number is higher than you hoped, treat it as a prompt for a supportive conversation, not as blame.
This article is for general education. It does not replace personalised medical advice, diagnosis or treatment.
Important: This information is for general education and does not replace personalised medical advice, diagnosis or treatment. Speak with an appropriate qualified healthcare professional about your health.
