Hemoglobin is a protein in your red blood cells which carries oxygen throughout the body. When hemoglobin is chemically linked to glucose in your blood, it is said to have been glycated. Glycated hemoglobin is also called HbA1c or glycohemoglobin.

The A1c (HbA1c) test aims to measure how much sugar is attached to your hemoglobin. The higher your blood glucose levels are, the more HbA1c you will have.

Healthy red blood cells survive in the body for about 3 months, after which they get destroyed. So, HbA1c test is used to estimate your average blood glucose levels over the 3 months before the test.

When should an HbA1c test be done?

You may have an HbA1c test done as part of a routine medical visit. Your doctor may recommend you for an HbA1c test if you have certain symptoms of diabetes, which may include:

• Urinating more often
• Intense thirst
• A need to eat more often
• Unintended weight loss
• Blurred vision
• Fatigue

The test can be used to diagnose diabetes and prediabetes, a condition where blood glucose is higher than normal but not high enough to qualify as diabetes.

If you are prediabetic, you will get tested every 2 years, or more often if necessary.

If you are diabetic, the first test is a baseline test. Thereafter, your doctor will tell you how regularly you need to be tested, depending on many personal factors. The test will be used to monitor how well your blood glucose levels are controlled and may be used to determine when to change your medications.

If you have a normal initial HbA1c, you may still to get tested every 3 years if you:

• Are 45 years or older.
• Are younger than 45 years, but you have risk factors for diabetes such as high blood pressure, high blood cholesterol, obesity, family history of diabetes and personal history of gestational diabetes (high blood glucose during pregnancy).

What should I do before the test?

You do not need to fast or prepare in any other way for the test.

How is the test done?

A nurse or phlebotomist will collect blood from your vein into a blood collection tube. The blood is taken to a laboratory where it is analyzed.

Blood can also be collected from your finger. The chosen finger will be cleaned with disinfectant and pricked by a small needle. The blood will be collected into a container and then analyzed. Your results will be back with minutes.

What do the results mean?

HbA1c is usually reported as a percentage of your hemoglobin that is attached to glucose. Your test is normal if your HbA1c level is less than 5.7%. If the level is above 5.7%, your doctor may need to check your current blood sugar levels or your blood sugar levels after an overnight fast.

You will be diagnosed with prediabetes if your HbA1c is 5.7%-6.4% and:

• fasting blood glucose is 100-125 mg/dl
• current blood glucose is 140-199 mg/dl

If you’re prediabetic, you are at higher risk of developing diabetes over time.

You may be diagnosed with diabetes if your HbA1c is 6.5% or more and:

• fasting blood glucose is 126 mg/dl or more
• current blood glucose is 200 mg/dl or more

Your doctor may need to report these tests to confirm that you have prediabetes or diabetes.

The results from your HbA1c test may also be interpreted as average blood glucose (eAG) of the past 3 months. Like the self-monitoring blood glucose test, average blood glucose is reported as mg/dl. Unlike continuous glucose monitoring, average blood glucose does not show how your blood glucose fluctuates throughout the months.

A comparison between HbA1c and average blood glucose is shown below.

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What is the target level of HbA1c?

For most people living with diabetes, the target HbA1c is usually 7%. But, the desired HbA1c may vary from one person to another. Your doctor may recommend a specific target depending on your age, testing interval, diabetes-related complications, other medical conditions and many other factors.

What can affect the results of an HbA1c test?

There are conditions or medications which can influence your test results. You may have:

Falsely high results if you:

• Have low iron levels
• Have low vitamin B12 levels
• Have high triglycerides in blood. Triglycerides are a type of fat in your body.
• Have had your spleen surgically removed
• Take certain HIV medications or medicines that suppress your immune system

Falsely low results if you:

• Have liver disease
• Have kidney disease
• Are pregnant
• Receive a blood transfusion
• Bleed significantly
• Take alcohol
• Live at high altitude
• Take iron supplements

Your test may be impacted by the type of hemoglobin you have. A person’s type of hemoglobin is determined by their genes. The most common form of hemoglobin is HbA, and some people have less common forms of hemoglobin known as hemoglobin variants. There are many hemoglobin variants, and they are more common in people of West African, Hispanic, South East Asian and Chinese descent. You may need to do a blood test to find out what type of hemoglobin you have.

How can I lower my HbA1c level?

Whether you are diabetic or prediabetic, achieving your HbA1c targets may be difficult but will reduce your likelihood of getting complications caused by high blood glucose levels.

If your HbA1c is above your target level, your doctor may change the dose or dosing schedule of your medications. In certain cases, changing your medication altogether may help you to control your blood sugar levels better. A combination of medications and lifestyle habits can help you reduce your HbA1c level. You may need to:

• Eat a diabetes-friendly diet. You will need to eat a balanced diet while watching how much carbohydrate-rich food you eat. You may need to avoid sugar-sweetened beverages and other processed sweets. Talking to your nutritionist will help you understand what to eat and how to balance your meals.
• Exercise regularly. Exercising helps your body to use more glucose and increases how well your cells respond to insulin. When exercising, you need to aim for at least 30 minutes of vigorous exercise a day, at least 5 days a week.
• Lose weight, if you are overweight. Your doctor may set weight targets for you depending on personal factors.
• Stop smoking.

What should I remember?

The HbA1c test is a crucial tool in managing diabetes, providing an overview of your blood sugar levels over the past 3 months. It helps you and your healthcare team assess how well your diabetes is being controlled and guides treatment decisions.

By regularly monitoring your HbA1c levels, you can take proactive steps to manage your diabetes and reduce the risk of complications. Maintaining an HbA1c level within your target range, through healthy lifestyle choices and medication if needed, is key to living a healthier life with diabetes.