Your HbA1c value tells you how high your blood sugar was on average over the past two to three months. Unlike a single glucose reading, HbA1c does not show a snapshot but a longer trend. That is why doctors use this value to detect and monitor diabetes and prediabetes.
I notice that many women know their blood sugar matters, but do not really know what that one HbA1c value on their result means. In this article I explain what HbA1c is, which values are normal, what a raised result can mean and when testing is useful. The cut-off values can differ per guideline, and your doctor always assesses your result together with your symptoms and your situation.
What is the HbA1c value?
HbA1c stands for glycated haemoglobin. Haemoglobin is the protein in your red blood cells that carries oxygen, and part of it binds sugar from your blood. The higher your blood sugar was on average, the more sugar is attached to it.
Because your red blood cells last about eight to twelve weeks, HbA1c gives an average of your blood sugar over that period. A single meal or a bad night therefore barely changes the value. That makes HbA1c a stable measure, while a single glucose reading can swing from hour to hour.
In the Netherlands HbA1c is expressed in millimoles per mole, abbreviated mmol/mol.
What is a normal HbA1c value?
In people without diabetes HbA1c usually sits below 42 mmol/mol. According to the guideline of the Dutch College of General Practitioners (NHG), a value from 48 mmol/mol points to diabetes, and the range between 42 and 47 mmol/mol to a raised risk. These limits are agreements, not hard laws of nature.
| Category | HbA1c (mmol/mol) | What it can mean |
|---|---|---|
| Normal | Below 42 | Your blood sugar was on average in a healthy range over the past weeks. |
| Prediabetes (raised risk) | 42 to 47 | Your blood sugar is slightly raised, which can point to a raised risk of diabetes. |
| Diabetes | 48 or higher | Fits with diabetes, though your doctor never makes the diagnosis on one value alone. |
These cut-off values can differ slightly per guideline and per laboratory. They also do not simply apply during pregnancy, where other limits are used. Your doctor always assesses your result together with your symptoms, your age and earlier measurements.
A value just below a limit is no reason to panic, and a value just above it is not immediately a diagnosis. It is about the whole picture, not one number.
What does a raised HbA1c mean?
A raised HbA1c means your blood sugar was on average higher than desired over the past weeks. That can fit with prediabetes or diabetes, but on its own it says nothing about the cause. Your doctor looks at your whole picture before drawing any conclusion.
A common reason behind rising blood sugar is that your body becomes less sensitive to insulin. In women this can relate to factors like PCOS, weight and menopause. In our pillar on insulin resistance in women and which blood values to test you can read how that process works.
Sometimes a raised result is temporary, for example due to an infection or medication. That is why an abnormal value is usually repeated once before anything is concluded. So always discuss a raised result with your GP.
HbA1c and prediabetes: where is the line?
Prediabetes is the phase where your blood sugar is higher than normal, but not yet high enough for a diagnosis of diabetes. In HbA1c terms that usually falls in the range of 42 to 47 mmol/mol. It is a signal, not a disease in itself.
This phase matters because you often still have influence over it. With attention to food, movement and weight, blood sugar drops again in many people. The Diabetes Fonds explains that for many people prediabetes is a reversible moment.
Want to know how to recognise prediabetes and which values belong to it? Then read on about recognising prediabetes through symptoms and blood values. A single HbA1c is never the whole story here.
When should you test your HbA1c?
Having your HbA1c drawn is useful with symptoms that can fit a high blood sugar, or with a raised risk. Think of a lot of thirst, frequent urination, tiredness or a family member with diabetes. It can also be sensible with overweight, PCOS or after gestational diabetes.
You do not have to be fasting for an HbA1c test, which makes it practical. According to the RIVM and the NHG standard, HbA1c is one of the ways to detect diabetes, alongside a fasting glucose measurement. Which test suits you depends on your symptoms and your risk.
Do you have vague symptoms or are you in doubt? Then read what the signals are and when measuring makes sense in our article on high blood sugar, the symptoms and when to test.
Testing your HbA1c yourself
If you want to map your HbA1c and blood sugar without first visiting your GP, you can do so at Lunara without a referral. You order online, have blood drawn in the morning at one of the more than 750 locations, and your result is assessed by a BIG-registered doctor. The Diabetes blood test looks at your HbA1c and your fasting glucose, among other things.
On your result you see both your HbA1c and your fasting glucose, with an explanation per value. Together they give a fuller picture than either one alone.
Important: testing yourself does not replace the care of your GP. It is meant as a starting point for a conversation and as a way to keep an eye on things. You always discuss an abnormal result with a doctor, who looks at your whole situation.
Frequently asked questions
Do I have to be fasting for an HbA1c test?
No, for HbA1c you do not have to be fasting. The value is an average over weeks, so what you ate that morning does not change the result. For a fasting glucose measurement you do have to be fasting.
What is the difference between HbA1c and glucose?
Glucose is your blood sugar at the moment of the draw, a snapshot. HbA1c is the average of your blood sugar over the past two to three months. Doctors often use them together because they complement each other.
How quickly does my HbA1c change?
Because red blood cells are replaced slowly, HbA1c changes gradually. A change in lifestyle or treatment usually shows clearly only after six to twelve weeks. Measuring more often than every few months therefore makes little sense.
Can my HbA1c be too low?
A low HbA1c is usually not a problem in people without diabetes. With some blood conditions or a short lifespan of red blood cells the value can turn out unreliably low. If you doubt a strikingly low result, discuss it with your doctor.
Does HbA1c count during pregnancy too?
During pregnancy other limits apply and gestational diabetes is usually detected with a sugar test, not with HbA1c. Always discuss your blood sugar in that period with your midwife or doctor. The values in this article apply to the situation outside pregnancy.
Does a raised HbA1c mean diabetes straight away?
Not automatically. A raised value is a signal that your doctor usually repeats once and assesses together with your symptoms. Only then is it decided whether there is prediabetes, diabetes or something temporary.
References
- Dutch College of General Practitioners (NHG). NHG guideline Diabetes mellitus type 2. NHG.
- Thuisarts.nl. I have type 2 diabetes and I want to know whether I have diabetes. Based on NHG guidelines.
- RIVM. Diabetes: figures and detection. National Institute for Public Health and the Environment.
- Diabetes Fonds. Prediabetes and blood sugar. Diabetes Fonds.
Every blood test result through Lunara includes a professional assessment by a BIG-registered doctor. Blood testing through Lunara is meant as an addition and does not replace the care of your GP. For a diagnosis or treatment, discuss your results with your GP.
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