HbA1c Blood Test

HbA1c blood test measures the amount of glycated haemoglobin in your blood and provides you with the average blood sugar (glucose) levels for the last two to three months. It reflects the amount of glucose that binds to haemoglobin in red blood cells.

What is HbA1c?

HbA1c (haemoglobin A1c) is a form of haemoglobin that is chemically linked to glucose (sugar). It forms when glucose in the bloodstream attaches to haemoglobin in red blood cells. Since red blood cells live for about 120 days, HbA1c reflects the average level of blood glucose over the past two to three months.

HbA1c is measured to assess how well blood sugar is being managed over time, particularly in people with diabetes. It’s a key marker for diagnosing diabetes and evaluating long-term glucose control in those who already have the condition.

Why have a HbA1c Blood Test?

The HbA1c blood test is essential for several reasons:

• It helps diagnose both type 1 and type 2 diabetes by measuring long-term blood sugar levels, and it can also identify pre-diabetes, a condition where blood sugar levels are elevated but not high enough to be classified as diabetes.
• For those already diagnosed with diabetes, the HbA1c test provides a clear picture of blood sugar control over the past 2-3 months, allowing doctors to assess the effectiveness of treatment plans such as diet, medication, or insulin therapy. Regular monitoring of HbA1c levels is crucial for preventing long-term complications associated with poorly controlled diabetes, including heart disease, kidney failure, nerve damage, and vision problems. Additionally, the HbA1c test does not require fasting, making it a more convenient option compared to some other blood sugar tests.
• Long-term view of glucose control is vital for both managing and preventing diabetes-related complications.

Knowing your HbA1c level and what you can do to lower it will help you reduce your risk of complications. This means getting your HbA1c checked regularly.

What do HbA1c Blood Test Results

Since red blood cells live for about three months, the test provides an overall picture of long-term blood sugar control. HbA1c is often used to diagnose and monitor diabetes and pre-diabetes. A higher HbA1c percentage indicates higher blood sugar levels and an increased risk of diabetes-related complications.

You should get your HbA1c test results pretty quickly. These results help you and your healthcare team decide if any changes are needed in your lifestyle, treatment or medication to manage your blood sugar better. It’s also important that you understand the number you receive. Many people find it useful to write their results in a diary to keep track of them and notice any patterns over time.

Your HbA1c levels can change for a variety of reasons, like if you’re unwell, taking medications such as steroids, going through lifestyle changes, or feeling stressed or depressed. You and your healthcare team should set a target level for you to aim for if you have been diagnosed with diabetes. While it’s not always easy to stay in your target range, it’s really important to do your best, as even slightly elevated levels over time increase the risk of serious complications.

Here are the typical HbA1c result ranges:

• Normal: Below 5.7%
• Pre-diabetes: 5.7% to 6.4%
• Diabetes: 6.5% or higher

A high HbA1c means you have too much sugar in your blood. This means you’re more likely to develop diabetes complications, like serious problems with your eyes and feet. Even a slightly raised HbA1c level makes you more at risk of serious complications.

For people with diabetes, the target HbA1c level is usually below 7%, though this can vary based on individual health goals.

How does HbA1c differ from a blood glucose level?

HbA1c gives a longer-term picture, like an average, of how high your blood sugar has been over the last 2-3 months. It’s often taken from a blood sample from your arm, though it can also be checked with a finger-prick test.

On the other hand, a blood glucose level measures the amount of glucose in your blood at a single moment—right when the test is done. This is often done with a fasting glucose test, which can also be taken from either a finger-prick or a blood sample from your arm.

While a fasting glucose test shows what your blood sugar is right now, the HbA1c test tells you how your average levels have been over time.

HbA1c can be measured as a percentage (DCCT unit) or in mmol/mol (IFCC unit), with mmol/mol being the standard in the UK since 2009. Just remember, HbA1c (in mmol/mol) is different from a blood glucose level, which is measured in mmol/l.

When should HbA1c levels be tested?

• When Diagnosing Diabetes or Pre-diabetes: If you’re being screened for diabetes or pre-diabetes, your doctor may request an HbA1c test to assess your long-term blood sugar levels.
• Every 3 to 6 Months for People with Diabetes: If you have diabetes, your healthcare provider will likely recommend testing your HbA1c every 3 to 6 months to monitor how well your blood sugar is being managed. This helps track long-term control and adjust treatment if necessary.
• After a Change in Treatment: If there’s a change in your medication, diet, or lifestyle, your doctor might schedule an HbA1c test to see how these adjustments are affecting your blood sugar control.
• More Frequently if Blood Sugar is Uncontrolled: If your blood sugar levels are unstable or not well controlled, your doctor may suggest testing more often to closely monitor your condition.

Regular testing helps ensure that your blood sugar levels stay within a healthy range and reduces the risk of complications from diabetes.

What are the benefits of lowering your HbA1c?

Two large-scale studies – the UK Prospective Diabetes Study (UKPDS) and the Diabetes Control and Complications Trial (DCCT) – demonstrated that improving HbA1c by 1% (or 11 mmol/mol) for people with type 1 diabetes or type 2 diabetes cuts the risk of microvascular complications by 25%. These include damage to the:

• retina (retinopathy)
• nerves (neuropathy)
• kidneys (diabetic nephropathy)

Research has also shown that people with type 2 diabetes who reduce their HbA1c level by 1% are: ^[1]

• 19% less likely to suffer cataracts
• 16% less likely to suffer heart failure
• 43% less likely to suffer amputation or death due to peripheral vascular disease