HbA1c Explained: What Your Number Actually Means
HbA1c is a blood test that estimates your average blood glucose level over the previous two to three months. Unlike a finger-prick glucose reading, it is not a snapshot of one moment.
What does HbA1c measure?
Glucose in the blood attaches to haemoglobin, a protein inside red blood cells. The HbA1c test measures how much glucose has attached over the life of those cells.
Results are commonly reported in mmol/mol in the UK, and sometimes as a percentage.
What is a normal HbA1c range?
For diagnosis and risk assessment, commonly used UK thresholds are:
| HbA1c result | General meaning |
|---|---|
| 41 mmol/mol or below | Usually not in the high-risk range for type 2 diabetes |
| 42–47 mmol/mol | Increased risk / prediabetes range |
| 48 mmol/mol or above | May indicate diabetes and needs clinical assessment or confirmation |
An HbA1c result does not give the full picture for everyone. Pregnancy, some blood disorders, recent blood loss and conditions affecting red blood cells can affect how reliable the result is.
Why trends matter
Your target, if you have diabetes, should be personalised with your healthcare team. It can depend on your type of diabetes, treatment, risk of low blood sugar and other health conditions.
One result is useful, but a series of results can show whether things are changing over time. Log HbA1c results in Pulse to keep them alongside your glucose and blood pressure readings.
What should you do with a result?
Do not self-diagnose based on an online chart. Discuss results with your GP, diabetes team or healthcare professional, especially if you have symptoms such as thirst, frequent urination, unexplained weight loss or tiredness.