What is a normal HbA1c level?

A normal HbA1c level is below 42 mmol/mol. Readings between 42 and 47 mmol/mol suggest prediabetes, while 48 mmol/mol or above indicates diabetes.

How often is HbA1c tested?

HbA1c is typically checked at a diabetes review every three to six months. It may be tested more often if your treatment has recently changed.

What is the difference between HbA1c and a finger-prick test?

HbA1c shows your average blood glucose over the past two to three months, while finger-prick tests show day-to-day variation. Both are useful and are often used together to guide treatment.

Can anaemia affect HbA1c results?

Yes, certain blood conditions including some types of anaemia can skew HbA1c results. Your GP will take this into account when interpreting your reading.

HbA1c blood test: What to Expect

Quick answer

What is an HbA1c blood test?

An HbA1c blood test measures your average blood glucose level over the past two to three months, and is used to diagnose and monitor diabetes. No fasting is needed beforehand. Target levels vary between individuals, so your diabetes team will agree a personal goal with you.

What HbA1c measures

HbA1c stands for glycated haemoglobin, which is sugar that has become attached to red blood cells. Because red blood cells last for several weeks, this measurement reflects your average blood glucose exposure over that time rather than a single snapshot.

How HbA1c is used for diagnosis and monitoring

HbA1c is used both to screen adults who are at higher risk of diabetes and to monitor people who already have the condition. Treatment targets are individualised, meaning your diabetes team sets a goal that is appropriate for your own health and circumstances rather than applying a single target to everyone.

Improving your HbA1c level

HbA1c levels can often be improved through changes to diet, physical activity and weight, alongside medicines where these are needed. Diabetes education programmes can also help by giving practical guidance on managing these changes day to day.

Limitations of the HbA1c test

Certain types of anaemia and other blood conditions can affect the accuracy of an HbA1c result, which is why your GP interprets it alongside your wider health picture. HbA1c is also not designed to detect episodes of hypoglycaemia, so other monitoring methods are used for that purpose.

Common questions about the HbA1c blood test

What is a normal HbA1c level?: A normal HbA1c level is below 42 mmol/mol. Readings between 42 and 47 mmol/mol suggest prediabetes, while 48 mmol/mol or above indicates diabetes.
How often is HbA1c tested?: HbA1c is typically checked at a diabetes review every three to six months. It may be tested more often if your treatment has recently changed.
What is the difference between HbA1c and a finger-prick test?: HbA1c shows your average blood glucose over the past two to three months, while finger-prick tests show day-to-day variation. Both are useful and are often used together to guide treatment.
Can anaemia affect HbA1c results?: Yes, certain blood conditions including some types of anaemia can skew HbA1c results. Your GP will take this into account when interpreting your reading.

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HbA1c blood test