Haemoglobin A1c, HbA1c, A1c… You’ve probably heard these terms before, but what do they actually mean? What is an HbA1c test? What is a “normal” HbA1c level? What can you do to lower your HbA1c? These are great questions. We’ve put together everything you need to know about HbA1c here.
Hemoglobin is the part of your blood that carries oxygen and is what gives your blood its red color. When glucose is processed by your body and enters your bloodstream, a small amount of it attaches to this hemoglobin, binding with it to produce glycated hemoglobin (commonly known as HbA1c). When your body has trouble using glucose effectively, the amount in your body increases.
If your body can't use glucose effectively and the amount of glucose in your blood increases, more glucose will attach to your hemoglobin, raising your HbA1c levels. Doctors use HbA1c levels to understand your average blood sugar levels over the past three months. Because red blood cells are constantly replaced and live for approximately 90 to 120 days, your HbA1c measurement reflects the average blood sugar levels over the past 8 weeks.
People with diabetes will have their own target HbA1c as discussed with their healthcare professional. The recommendation for most adults with diabetes is an HbA1c level of less than 53 mmol/mol (7%).1 Guidelines from the American Diabetes Association (2025)1 say that a normal HbA1c is 39 mmol/mol (5.7%) or lower. However, people who are at risk of developing diabetes, and therefore classified as having prediabetes, would have an HbA1c of between 39 and 47 mmol/mol (5.7 and 6.4%). In someone without diabetes, a high HbA1c of 48 mmol/ mol (6.5%) or higher could indicate they have developed diabetes.
Because HbA1c estimates your average blood glucose over a period of time, the higher your HbA1c level is, the more glucose has been in your blood. This can increase the risk of you developing diabetes-related complications, such as eye, foot and kidney problems.
The American Diabetes Association recommends measuring HbA1c at least twice a year in patients who are meeting treatment goals, and quarterly when therapy has changed or targets are not being met. This highlights its essential role in shared decision-making between patients and healthcare professionals.2
There are several differences between HbA1c and blood glucose levels.
Knowing your HbA1c level is one matter, but actually understanding what it means is the important thing. Data isn’t useful if you can’t understand it, right?
Because HbA1c is an average of blood sugar levels, a high or above target HbA1c means that blood sugar levels have been consistently above target over the 2-3 months prior to the HbA1c measurement. This suggests that your current therapy plan may not be working for you, and means your healthcare professional can look at making adjustments or changes to help you reduce your HbA1c.
You may find it useful to keep a record of your HbA1c levels, maybe in a diary or electronic logbook, to see if you can spot any patterns or trends. What’s important though, is trying to keep your HbA1c level within your target as much as possible.
Your HbA1c level will generally vary from measurement to measurement depending on the amount of glucose in your blood. If you’ve had a period of high blood glucose levels over the weeks before the measurement is taken, then your HbA1c level will reflect this.
There are some other factors that can impact your blood glucose levels and, as a result, change your HbA1c level, these include:
Some medications, such as steroids, can also impact your HbA1c, as can some medical conditions that affect the red blood cells. Please speak to your healthcare professional if this is the case.
It’s important to try and keep your HbA1c level within your target range. We know this isn’t easy, but there is evidence to suggest that every 11 mmol/mol (1%) HbA1c reduction can lead to a significant reduction in the risk of diabetes related complications.2
If your HbA1c level is above your individual target, there are several steps you and your healthcare professional can take to bring it down to target.
Your healthcare professional may also review your medication and make some adjustments; they may even make a change to the medication you are taking if you are on oral medications.
As HbA1c is an average measurement, it doesn’t generally detect day-to-day variations in your blood glucose. For this reason, it is generally used in combination with a measure of variability, such as time in range or points in range, which show the amount of time spent above or below your target blood glucose range.
As you can see, HbA1c is a really important tool for you and your healthcare professional in managing your diabetes. It is not the only tool, as it will be used in combination with other measures, but it can be very valuable in giving an idea of how well managed your diabetes is. If you are unsure when your last HbA1c level was taken, please contact your healthcare professional to check and see when you should next have one.
Before making any changes to your lifestyle or medication, please speak to your healthcare professional to check it is suitable for you.
This content is provided for general information only. It is not intended to amount to advice on which you should rely – you must obtain professional or specialist advice from your healthcare professional before taking, or refraining from, any action on the basis of the content. Although we make reasonable efforts to ensure that the content is up to date, Roche makes no representations, warranties or guarantees, whether expressed or implied, that the content is accurate, complete, up-to-date or that it should be relied upon.
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