What is the Haemoglobin A1c (Hb A1c) test and why does it matter?
Medically reviewed by Dr Sultan Linjawi, Endocrinologist & Diabetes Specialist — November 2025
The prevalence of type 2 diabetes
It’s no secret how devastating the effect of diabetes is worldwide. Globally, diabetes is a major contributor to early illness and death. The World Health Organisation estimated that diabetes was the seventh leading cause of death in 2016, with diabetes being a direct cause of 1.6 million deaths worldwide (Diabetes).
Global statistics
The 8th edition of the International Diabetes Federation’s (IDF) Diabetes Atlas released in 2017, estimated that:
- One in 11 people have diabetes (425 million)
- One in two adults with diabetes are undiagnosed (212 million)
- 12% of global health expenditure is spent on diabetes (USD$727 billion)
- Every 6 seconds a person dies from diabetes
IDF also estimated that by 2040:
- One in 10 adults will have diabetes
- Diabetes-related health expenditure will exceed USD$802billion
How is a person with diabetes monitored?
There are a number of ways to measure how a person with diabetes is doing. This can include how they feel, whether they have complications and by looking at the result of certain blood tests. The best method to track how a person with diabetes is doing is a simple blood test called the Haemoglobin A1c or Hb A1c test.
What is the Hb A1c test?
The Hb A1c test, or the glycated haemoglobin A1c test, is a blood test that can be taken at any time and is not affected by food. You don’t need to fast before taking the test. It gives an indication as to what your average blood glucose levels have been over the previous three months, by measuring the percentage of a certain type of haemoglobin, called HbA1 that has been altered by a glucose molecule has attached to it. After glucose has attached to haemoglobin A1 (HbA1) it is given a new name, Haemoglobin A1c or Hb A1c.
Try using our HbA1c tool to see where you are at.
What is haemoglobin?
Haemoglobin is the iron-containing protein that is responsible for transporting oxygen in red blood cells. It helps to carry oxygen from our lungs to the rest of the body.
There 1 main type of haemoglobin in red blood cells, haemoglobin A (Hb A) which contains 2 alpha chains and 2 beta chains. When glucose binds to HbA, it binds to specific part of the beta chain and we give it a new name to differentiate it from normal haemoglobin. The molecule with glucose attached is called haemoglobin A1c or HbA1c.
The HbA1c test reports how much HbA1c there is compared to the other haemoglobin subtypes.
What do the different HbA1c readings mean?
It is normal for all people to have some glucose attached to haemoglobin A1. In people with diabetes, the higher the blood glucose levels are, the more glucose you have attached to haemoglobin.
A person without diabetes has a HbA1c level below 5.7%
Someone with prediabetes (sometimes called borderline diabetes), has a HbA1c level between 5.7 and 6.4%
In people with diabetes, a HbA1c level of 6.5% or higher, from two separate tests, can indicate diabetes.
Check your Hb A1c with our Hb A1c tool
You can check your eAG using the Hb A1c tool below. The tool can help you to understand what your average blood glucose value has been from the previous 3 months. This information can help you to determine whether your current diabetes management is working for you or not.
Let's assess your
Risk of Developing Complications
What type of diabetes do you have?
Choose either percentage or mmol/mol depending on what is written on your blood laboratory result.
%
Range 5 - 16%
Low risk
HbA1c
Estimated Average Glucose (eAG)
mg/dL
mmol/L
Your HbA1c is in the Normal Range
Your blood sugar levels over the past 2-3 months have been within the normal, healthy range. This result suggests a low risk of diabetes.
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This tool provides general information only and does not replace medical advice. Always consult your healthcare provider about your results and personal targets.
Why are there different values reported with the Hb A1c?
Historically the Hb A1c was reported based as the percentage of haemoglobin A1 altered by the attachment of glucose. Typically this would give an HbA1c range 4-16% where under 5.7% is normal, 5.8-6.4% is the range for borderline or prediabetes and greater than 6.5% is diagnostic of diabetes.
In 2011 a new reporting method was developed by the International Federation of Clinical Chemisty (IFCC) as a new standard using mmol/mol rather than percentage. This laboratory report was based on measuring the actual amount of Hb A1c rather than reporting the percentage compared to other haemoglobin molecules.
The IFCC range would be between 20 and 150mmol/mol with the diabetes range being above 48mmol/mol.
What is estimated Average Glucose (eAG)?
The estimated Average Glucose (eAG) is a relatively new term in diabetes management and tries to give a person an indication of what the average blood glucose levels would be from the Hb A1c result (Translating the Hb A1C Assay Into Estimated Average Glucose Values). The eAG converts Hb A1c value to an average blood glucose level in the units of measure seen by the patient on their blood glucose meters for daily self-monitoring (either mg/dL or mmol/L). The eAG is a way to show patients what their Hb A1c results are in the same units that they're more familiar with.
| Hb A1c as % | Hb A1c in mmol/mol | eAG as mmol/L | eAG as mg/dL |
|---|---|---|---|
| 5.0 | 31 | 5.4 | 97 |
| 6.0 | 42 | 7.0 | 126 |
| 6.5 | 48 | 7.8 | 154 |
| 7.0 | 53 | 8.6 | 169 |
| 8.0 | 64 | 10.1 | 183 |
| 9.0 | 75 | 11.8 | 212 |
| 10.0 | 86 | 13.4 | 240 |
| 11.0 | 97 | 14.9 | 269 |
| 12.0 | 108 | 16.5 | 298 |
What’s the difference between Hb A1c and the reading on my glucose meter?
A HbA1c reading is an estimated average of blood glucose levels from the previous three months. The reading on the glucose meter, is from a single point in time and can tell you what your blood glucose readings are at the time that you test.
These glucose readings can be variable and depend on what you’ve eaten or what medication you use, as well as a number of other factors.
What are the recommended Hb A1c target ranges for patients with diabetes?
For some patients, their doctor may provide them with their own personalised Hb A1c target range. There are general target ranges, as well as target ranges depending on other factors like age (child vs adult) or pregnancy.
Recommended Hb A1c target ranges for patients with type 2 diabetes
| Hb A1c Target | |
|---|---|
| General | <53 mmol/mol, <7.0% |
| Pregnancy or planning pregnancy | <42 mmol/mol, <6.0% |
| Children and adolescents | <53 mmol/mol, <7.0% |
Recommended Hb A1c target ranges for patients with type 1 diabetes
| Hb A1c Target | |
|---|---|
| General | <53 mmol/mol, <7.0% |
| Pregnancy or planning pregnancy | <53 mmol/mol, <7.0% |
| Children and adolescents | <58 mmol/mol, <7.5% |
To the point
- Hb A1c is a test used to estimated your blood glucose control over the previous 3 months
- There are a number of Hb A1c units of measure. Some of them can tell us the same information but in slightly different ways
- Depending on whether you have prediabetes, type 1 diabetes, type 2 diabetes, or gestational diabetes, you will have different Hb A1c goals. Your doctor may even recommend a Hb A1c that is specific to you.
