HbA1c Glucose Test for Diabetes – Everything You Need to Know

What is diabetes?

Diabetes mellitus is a group of diseases characterised by the chronic state of high blood sugar (hyperglycaemia). This is usually the result of a problem with the secretion or action of insulin, the hormone that controls our blood sugar level. Diabetes is a highly prevalent disease; in 2019, it was estimated that 9.3% of the world’s population suffered from some form of diabetes1. In this post, we will learn everything that you need to know about diabetes and the HbA1c glucose test.

Diabetes – Type 1 and 2

The two most common types of diabetes are type 1 and type 2.

Type 1 diabetes is a genetic disease, in which symptoms usually start in childhood. Individuals with this type of diabetes cannot secrete insulin and therefore struggle to control their blood sugar levels. This happens as a result of an autoimmune reaction, where the body attacks and destroys its own pancreatic beta cells, which are responsible for the production of insulin2.

Type 2 diabetes is a more complex disease, with symptoms that are almost unnoticeable in the early stages. This type of diabetes usually develops later in life – for most, in late adulthood. This can occur as a result of a wide set of lifestyle and environmental factors, as well as a genetic predisposition to diabetes (family history). Between 90-95% of diabetes patients suffer from this type of diabetes2.

The disease develops due to increasing insulin resistance, where the tissues that are targeted by the hormone become ‘desensitized’ to it. This means that the body requires higher insulin levels to control blood sugar levels. However, the higher insulin requirements cannot be met in type 2 diabetes because the insulin-producing pancreatic beta cells are damaged. This causes a myriad of symptoms that can eventually become life-threatening2.

Other types of diabetes

Type 1 and 2 are the two types of diabetes that are most well-known. There are, however, other types of diabetes, such as prediabetes and gestational diabetes.

Prediabetes is an asymptomatic state where a patient has blood sugar levels that are elevated but have not yet reached the diabetic threshold. This means that they are at higher risk of developing type 2 diabetes. However, not all prediabetic patients become diabetic. If diagnosed early, exercise and weight loss can significantly decrease the risk of developing the disease3.

Gestational diabetes is a serious pregnancy complication. This disease occurs in non-diabetic women who have begun to develop chronic hyperglycaemia during pregnancy. This occurs as a result of insulin resistance, as well as the dysfunction of pancreatic beta cells, much like in type 2 diabetes. Women who are overweight, obese, become pregnant at a late age or have a family history of diabetes are at higher risk of gestational diabetes4. Women who suffer from this and their babies are subsequently also at higher risk of developing diabetes.

What are the symptoms of type 2 diabetes?

Symptoms often take several years to develop in people who suffer from type 2 diabetes. Some of the symptoms include:

  • Increased urination, leading to increased thirst
  • Unexplained weight loss
  • Blurred vision
  • Feeling weak
  • Numbness or tingling in the feet or hands
  • Sores that don’t heal2

What does the HbA1c glucose test measure?

The haemoglobin A1c test (HbA1c), sometimes called the glycated haemoglobin test, measures the amount of haemoglobin (a protein found in red blood cells) bound to glucose in your bloodstream. This directly correlates to the average blood sugar levels in your body. And because red blood cells can live for up to 120 days, your HbA1c levels can reflect the average level of glucose in your blood over the last 3 months.

In the past, this test was only used to monitor patients with diagnosed diabetes. However, it has recently become an effective tool to diagnose different types of diabetes5.

This is because blood sugar levels in diabetics can often appear to be within the normal ranges at various times in the day. Therefore, an overview of blood sugar levels over the last 3 months gives a clear view of any chronic blood sugar level dysregulation. The results from this test will indicate the likelihood of diabetes – the higher the value, the higher your 3-month-average blood sugar levels.

Is there a difference between an HbA1c glucose test and the finger-prick blood glucose test?

Most of us are familiar with the finger-prick blood glucose test; people who suffer from diabetes often use these tests to check their blood glucose levels at a single point in time. This helps diabetes patients decide on what food to eat or what medication to take.

However, the finger-prick test should not be used as a diagnostic tool. This is because it provides a snapshot of your blood glucose levels at a single point in time, and therefore fails to represent any chronic or long-term irregularities.

The HbA1c test, in contrast, will reflect your average blood glucose levels over a long period of time, and therefore it will highlight chronic dysfunction of regulation of blood glucose levels.

In order to diagnose diabetes using a blood glucose ‘snapshot’, a healthcare professional can also carry out a Fasting Plasma Glucose test (FPG). They will ask you to fast for at least 8 hours, after which a blood sample is taken from your arm to check your fasting glucose levels.

When should you get an HbA1c glucose test?

If you have any symptoms that could be caused by undiagnosed diabetes, you should get tested using the HbA1c test.

There are also certain groups that are more at risk of developing type 2 diabetes than others. These people should routinely test for diabetes, even if they don’t have symptoms. This includes people6:

  • Over the age of 45
  • Between the ages of 19 and 44 who are obese or overweight
  • With a family history of diabetes
  • With high blood pressure

For people in these risk groups, regular testing can allow early diagnosis and therefore better management of symptoms and prevention of complications.

If you have already been diagnosed with diabetes, it is recommended that you take the HbA1c test at least twice a year7. This will give you and your doctor an indication of how well your diabetes has been managed over the previous 3 months.

What’s the normal value for an HbA1c Glucose test?

The World Health Organisation (WHO) outlines the following ranges for the diagnosis of diabetes:

  • Below 42 mmol/mol: healthy
  • Between 42 and 47 mmol/mol: glucose level dysregulation, possible prediabetes
  • 48 mmol/mol or over: diabetic

However, it has been shown that when looking at blood test results, optimal ranges can be a lot more indicative of your long-term health than reference ranges. This is especially important when testing for diabetes, as a test result that is within the ‘normal’ range does not necessarily equal perfect long-term health.

HbA1c - Reference range
HbA1c – Reference range (mmol/mol)
HbA1c - Optimal range
HbA1c – Optimal range (mmol/mol)

Therefore, ElevateMe uses optimal ranges that have been scientifically linked to low risks of diabetes in the future. These are:

  • < 20 mmol/mol – low
  • < 31 mmol/mol – Sub-optimal
  • < 38 mmol/mol – Optimal
  • < 48 mmol/mol – High – possible pre-diabetes
  • >48.01 mmol/mol – Very high

What does a high HbA1c test value mean?

A high HbA1c test value can indicate that you may be suffering from type 1 or 2 diabetes or prediabetes. It’s best to talk to your doctor if you are worried about your result.

High HbA1c levels in diabetics can also indicate poor diabetes management. In this case, your diet and medication routines may need to be reviewed by your doctor.

What does a low HbA1c test value mean?

Although high HbA1c may indicate the presence of diabetes, a result that is too low can also be a cause for concern. This low value may point to hypoglycemia (low blood sugar), which could be caused by various factors like poor diet, or other health issues, such as liver diseases. If your HbA1c value is low, it is recommended that you talk to your healthcare professional to understand the reason behind your result.

How can you reduce your HbA1c levels?

Reducing HbA1c levels comes hand-in-hand with controlling and preventing diabetes.

If you are diabetic, you can reduce your HbA1c value by taking the appropriate prescribed medication and sticking to good diabetes food and exercise practices.

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%8.

If you are not diabetic, but your HbA1c levels are elevated, you need to focus on the 3 main factors that have been scientifically proven to reduce the risk of developing type 2 diabetes9:

  • Exercising more regularly
  • Losing weight
  • Eating a healthier, more varied diet

What should you do before your HbA1c glucose test?

Unlike the finger-prick blood glucose test, your mealtimes don’t affect the results of the HbA1C test. That means you can eat and drink before your test. A blood sample will be taken from your vein (or your finger if you are doing the ElevateMe at-home blood test), after which it will be sent off to the lab.

Can the HbA1c test detect gestational diabetes?

The HbA1C test is not recommended as a diagnostic tool for gestational diabetes. This is due to the physiological changes that take place in the blood when a woman becomes pregnant. As a result of this, studies of HbA1c as a test for gestational diabetes have shown that it does not provide accurate or reproducible results10.

Instead, pregnant women can get an oral glucose tolerance test (OGTT). This test assesses the body’s response to a dose of glucose after 8 hours of fasting. First, a blood sample is taken from the arm, after which the patient is given a glucose drink. Then, another blood sample is taken 2 hours later11.

What are the limitations of the HbA1c glucose Test?

As mentioned previously, one of the main limitations of the HbA1c test is that it cannot be used to detect gestational diabetes.

Because it relies on the measurement of haemoglobin, it may also be inaccurate in individuals with anaemia who have insufficient haemoglobin.

Summary

The HbA1c test is crucial for both diabetics and people without diagnosed diabetes. Its optimal ranges can help you understand if you need to adjust your lifestyle to prevent different types of diabetes. Getting an HbA1c test regularly helps you stay on top of your health, as diabetes is a manageable disease with early intervention.

The ElevateMe health program includes an HbA1c test, as well as 20 other essential biomarkers tracked via a single blood test that reflects your overall health and well-being. We use Cato, our intelligent health algorithm, to analyse your results from the HbA1c test and create a tailored action plan. This will help you stay on top of your health by preventing diabetes.

ElevateMe’s health plans are flexible and allow you to re-test your blood every 3, 6 or 12 months – perfect for people suffering from diabetes who want to keep track of how well their diabetes is being managed.

How’s your blood sugar? 

Did you know 1 in 11 adults in the world have some form of diabetes. The good news is that it’s highly manageable. Proper diet, overall health, and tracking are key.

Take an ElevateMe blood test today to capture 21 blood test insights and track your sleep, fitness, energy, metabolism, cognition, mood, and immunity.

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References

1 Saeedi, P., Petersohn, I., Salpea, P., Malanda, B., Karuranga, S., Unwin, N., Colagiuri, S., Guariguata, L., Motala, A.A., Ogurtsova, K., Shaw, J.E., Bright, D. and Williams, R. (2019). Global and regional diabetes prevalence estimates for 2019 and projections for 2030 and 2045: Results from the International Diabetes Federation Diabetes Atlas, 9th edition. Diabetes Research and Clinical Practice, [online] 157, p.107843.

2 Diagnosis and Classification of Diabetes Mellitus. (2009). Diabetes Care, [online] 33(Supplement_1), pp.S62–S69.

3 Bansal, N. (2015). Prediabetes diagnosis and treatment: A review. World Journal of Diabetes, [online] 6(2), p.296. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4360422.

4 Plows, J., Stanley, J., Baker, P., Reynolds, C. and Vickers, M. (2018). The Pathophysiology of Gestational Diabetes Mellitus. International Journal of Molecular Sciences, [online] 19(11), p.3342.

5 Florkowski, C. (2013). HbA1c as a Diagnostic Test for Diabetes Mellitus – Reviewing the Evidence. The Clinical biochemist. Reviews, [online] 34(2), pp.75–83.

6 National Institute of Diabetes and Digestive and Kidney Diseases. Risk Factors for Type 2 Diabetes | NIDDK. National Institute of Diabetes and Digestive and Kidney Diseases. Published May 19, 2021. Accessed May 19, 2021.

7 HbA1c – Understand the Test. Labtestsonline.org.uk. Published March 30, 2020. Accessed May 17, 2021.

8 Glycosylated haemoglobin & diabetes. HbA1c facts, units, diagnosis, testing frequency, limitations, control & conversion. How blood glucose levels link to A1c. Diabetes. Published January 15, 2019. Accessed May 19, 2021.

9 Reduction in the Incidence of Type 2 Diabetes with Lifestyle Intervention or Metformin. (2002). New England Journal of Medicine, [online] 346(6), pp.393–403.

10 Renz, P.B., Cavagnolli, G., Weinert, L.S., Silveiro, S.P. and Camargo, J.L. (2015). HbA1c Test as a Tool in the Diagnosis of Gestational Diabetes Mellitus. PLOS ONE, [online] 10(8), p.e0135989.

11 Labtestsonline.org. (2020). Glucose Tolerance Test | Lab Tests Online. [online]

HbA1c-test-for-diabetes

Written by Natalia Glazman

I'm a Biochemistry student at Imperial College, interested in all things immunology and pursuing a career in science communication.

24/05/2021

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