Glycated Haemoglobin (HbA1c): What it is and how to measure it

Glycated haemoglobin, also known as HbA1c, is one of the most important indicators in assessing blood glucose control. Unlike individual spot measurements of blood sugar, this test provides an overall picture of glucose levels over the preceding months.

In this article, we explain what glycated haemoglobin is, how to interpret the values, and what you can do to improve your results consistently.

What Is Glycated Haemoglobin?

Glycated haemoglobin (HbA1c) is a form of haemoglobin — the protein found in red blood cells — that binds to glucose present in the blood. When blood sugar levels are elevated, a greater amount of glucose becomes bound to this protein. Since red blood cells have an average lifespan of approximately 120 days, HbA1c serves as a reliable record, reflecting the average blood glucose levels over that period.

This makes glycated haemoglobin a fundamental clinical indicator, because, unlike instant measurements, it does not depend on a single isolated moment, but rather on a consolidated trend over time. This long-term perspective allows for more accurate monitoring on the effectiveness of treatment and diabetes management.

Glycated haemoglobin (HbA1c): what is it used for?

Glycated haemoglobin has several important clinical applications, particularly in the area of diabetes.

It is used as an indicator to:

• diagnose diabetes and pre-diabetes; 
• assess blood glucose control over time; 
• adjust treatment and management strategies; 
• predict the risk of diabetes-related complications.

Glycated Haemoglobin vs. Blood Glucose: What is the difference?

G lycated Haemoglobin (HbA1c) and blood glucose are two fundamental indicators in the assessment of blood sugar, but they provide different perspectives on control of blood sugar. 

G lycated haemoglobin reflects the average blood glucose levels over the preceding 2 to 3 months. This indicator results from the binding of glucose to haemoglobin in the red blood cells, providing a comprehensive and continuous picture of blood glucose control. It is therefore particularly useful for evaluating the effectiveness of treatment and identifying long-term trends.

Blood glucose, by contrast, corresponds to the measurement of glucose levels at a specific point in time. It can be assessed in different contexts, such as fasting, after meals, or on a continuous basis, and is essential for the day-to-day management of diabetes. These measurements help to understand how factors such as diet, exercise, and medication influence blood sugar levels throughout the day.

Glycated Haemoglobin (HbA1c): Reference Values

Glycated haemoglobin (HbA1c) values are expressed as a percentage and indicate the proportion of haemoglobin that is bound to glucose.

In general, the following ranges are recognised:

• Normal: lower than 5.7% 
• Pre-diabetes: between 5.7% and 6.4% 
• Diabetes: equal to or higher than 6.5% 

For people with diabetes, the usual target is to keep HbA1c below 7%, although this value may vary depending on age, health status, and medical guidance.

Glycated Haemoglobin (HbA1c): factors that may influence results

Although glycated haemoglobin (HbA1c) is a robust and widely used indicator for assessing long-term blood glucose control, certain factors can interfere with results and lead to less accurate interpretations.

One of the main aspects to consider is related to changes in red blood cells. Since HbA1c depends on the lifespan of these cells, any condition that affects their production, duration, or destruction may influence the values obtained. Furthermore, certain diseases or clinical conditions can alter the metabolism and composition of the blood, affecting the reliability of this indicator.

The main factors that may influence results include:

• anaemia or changes in red blood cells; 
• recent haemorrhages or blood transfusions; 
• kidney or hepatic diseases; 
• pregnancy; 
• genetic variants of haemoglobin (haemoglobinopathy). 

For these reasons, it is essential to always interpret glycated haemoglobin values with a healthcare professional, which takes into account the individual clinical context. When necessary, additional tests may be used to ensure a more accurate assessment of glycaemic control.

Glycated Haemoglobin (HbA1c): How to improve results

Improving glycated haemoglobin requires more than reducing isolated blood glucose spikes — it demands consistency over time and a holistic approach that encompasses both lifestyle and treatment. 

1. Adopt a balanced diet

Diet has a direct and continuous impact on blood glucose levels. Choosing balanced, fibre-rich meals — such as vegetables, fruits, wholegrains, and pulses — helps to slow glucose absorption and avoid sharp fluctuations. Reducing the consumption of simple sugars, sugary drinks, and ultra-processed foods is equally important. 

In addition, maintaining regular mealtimes and spreading carbohydrate intake appropriately throughout the day contributes to greater glycaemic stability.

2. Practice regular physical activity

Physical activity plays an essential role in improving insulin sensitivity, enabling cells to use glucose more efficiently. Aerobic exercises, such as walking, swimming, or cycling, help reduce blood glucose levels, whilst strength training helps increase muscle mass, which also supports glucose metabolism. 

Regularity is key; it is important to incorporate exercise into the weekly routine in a consistent manner that is adapted to each individual’s physical condition.

3. Monitor blood glucose

Regular blood glucose monitoring makes it possible to identify patterns and understand how the body responds to different stimuli, such as diet, stress, or exercise. This information is essential for adjusting day-to-day behaviours and avoiding both hyperglycaemia spikes and hypoglycaemia episodes. Over time, this practice contributes to more stable control, resulting in an improvement in HbA1c values.

4. Adhere to prescribed medication

When medication is required, strict adherence to it is crucial for keeping blood glucose levels within the recommended values. Medicines work in different ways — by increasing insulin production, improving its action, or reducing glucose absorption — and these medications must be used as directed by the doctor. Any adjustment must always be made under the supervision of a healthcare professional to ensure efficacy and safety.

5. Maintaining a healthy weight

Excess weight, particularly around the abdomen, is associated with insulin resistance, making blood glucose control more difficult. Even modest weight loss can significantly improve the body’s response to insulin and help reduce HbA1c levels. This process should be gradual and sustainable, built on consistent changes to diet and physical activity levels.

6. Ensuring regular medical follow-up

Follow-up with healthcare professionals is essential for the effective management of diabetes. Appointments allow the progression of HbA1c to be assessed, the treatment plan to be adjusted, and potential complications to be identified at an early stage. They also provide an important opportunity to address questions, reinforce strategies, and tailor recommendations to individual needs, which may change over time.

Glycated haemoglobin (HbA1c): frequently asked questions

Below, we answer some of the most common questions about glycated haemoglobin (HbA1c). 

What is the normal level of glycated haemoglobin? 

For a person without diabetes, the HbA1c reference value is generally below 5.7%. Values between 5.7 % and 6.4 % may indicate pre-diabetes, meanwhile a result of 6.5% or above is, as a rule, one of the criteria for a diagnosis of diabetes.

What can cause glycated haemoglobin levels to rise? 

A rise in HbA1c is caused by persistently elevated blood sugar levels over time. Factors such as an unbalanced diet, lack of physical exercise, stress, missed medication doses, or intercurrent illnesses can all contribute to this rise.

Is fasting required to measure HbA1c? 

No. Unlike the fasting blood glucose test, the glycated haemoglobin test does not require prior fasting. Since the test measures the average over the preceding months rather than the blood sugar level at that precise moment, eating before the sample is taken does not affect the final result.

Take care of your health with Quilaban Diabetes solutions

Glycated haemoglobin is an essential indicator for understanding and effectively managing diabetes. By providing an overall picture of blood glucose levels, it helps guide decisions and prevent long-term complications. 

Quilaban Diabetes offers innovative solutions to simplify diabetes management, promoting a more informed and consistent approach. Our commitment is to support each person on their journey, with tools that simplify monitoring and contribute to a better quality of life.