Hemoglobin Test for Diabetes

Hemoglobin Test for Diabetes

The hemoglobin test for diabetes could be one of the most important medical tests you get. The test, more accurately known as a glycated hemoglobin or A1C test, is closely related to blood sugar levels. It is used for diabetes diagnosis and management. You may use an A1C test for diabetes if you have risk factors for diabetes or you have diabetes. 

Here is what you should know about the glycated hemoglobin test for diabetes. You will learn:

  • What is hemoglobin A1C?

  • What is a hemoglobin A1C test for diabetes?

  • What is a normal A1C?

  • What should your A1C be?

  • How to bring down A1C levels.


What Are Hemoglobin and Glycated Hemoglobin?

Hemoglobin is a protein in healthy red blood cells. Its job is to deliver oxygen to the cells of your body. Hemoglobin picks up oxygen as your blood passes through your lungs. As your blood circulates throughout your body, hemoglobin releases the oxygen so that cells can use it for metabolism.

Glycated hemoglobin also goes by the names of A1C, HbA1C, and glycosylated hemoglobin. It refers to hemoglobin that has been “glycated.” That means that a molecule of glucose in your blood has “bound” (attached to) a molecule of hemoglobin. At least some amount of glucose is always floating around in your blood, and some of it naturally binds to hemoglobin to form A1C or glycated hemoglobin.


Glycated Hemoglobin and Your Blood Sugar

A higher level of blood sugar (blood glucose) means that more hemoglobin will be glycated. That is, your A1C (glycated hemoglobin) will make up a higher percentage of your total hemoglobin. A1C is so closely tied to blood sugar that it is used to calculate your estimated average glucose (eAG) over the past 3 months.


Why is the timeframe 3 months? Red blood cells, which contain your body’s hemoglobin, have a lifespan of 90 to 120 days, or about 3 to 4 months. 


How Glycation Affects Hemoglobin’s Function

It is normal and healthy for a small amount of your hemoglobin to become glycated while the rest of your hemoglobin does not, but high A1C levels are concerning. The first reason is that glycated hemoglobin is less functional than regular hemoglobin because it is not as good at releasing oxygen to cells as your blood circulates.[1]


High A1C and Diabetes

Diabetes is the real reason to pay attention to high A1C. A high value is a sign of high blood sugar levels, as you know from seeing the link to estimated average glucose over the past 3 months. Slightly above-normal blood glucose means prediabetes, and blood sugar levels above that mean that you have diabetes.

Your A1C test results can give you a glimpse of something else, too. Just as blood glucose binds to your hemoglobin and impairs their function, it binds to other proteins in your blood and makes them less healthy, too. If your glycated hemoglobin percentage is higher than normal, you are likely to have higher-than-normal glycation and associated health problems in the following areas:[2]


What to Expect for an A1C Test

A glycated hemoglobin test checks for glucose bound to hemoglobin and tells you your average blood sugar. The test is a simple blood test that you can get at almost any lab. Just ask your doctor or call ahead to be sure that you can get your A1C test at your regular lab. Unlike for a regular blood sugar test, you do not need to fast for your HbA1C test. 

You will get the results within days or weeks, as you normally do with your doctor and lab. Your doctor should help you understand the results if you have questions.


A1C Chart

An A1C chart can help you understand the results of your glycated hemoglobin test for diabetes.

Category HbA1C Values Estimated Average Glucose (eAG)
At least 6.4%
At least 137 mg/dl
5.7 to 6.4%
117 to137 mg/dl
Less than 5.7%
Less than 117 mg/dl

Why YOU May Need a Hemoglobin Test for Diabetes

The glycated hemoglobin test is used to check for prediabetes and diabetes, and to monitor diabetes if you have it. 

Who needs an A1C test? Lots of people do. You might, if:

  • You have diabetes. 30 million Americans, or 1 out of 8 adults, do.[3]

  • You have prediabetes. 84 million Americans, or 1 out 3 adults, do.

  • You have risk factors, such as excess weight or physical inactivity, for prediabetes, diabetes, or insulin resistance. 2 out of 3 adults are overweight or obese,[4] and 3 out 4 Americans do not meet recommendations for exercise.[5]

  • You have symptoms of diabetes, such as excessive thirst or urination, unexplained weight loss or fatigue, blurred vision, or darkened skin on the back of your neck.

  • You got a high random blood glucose test result, or a high fasting blood glucose result, and your doctor wants to check your sugar another way.

  • You got a very low blood glucose test result, and your doctor wants to check whether that could be a sign that you may have poor glucose control.

Are you unsure whether you have diabetes, prediabetes, or risk factors? If you are not sure, you might want to ask your doctor about an A1C test for blood sugar. You can easily have high blood sugar without feeling any signs.


Goal A1C

Your goal A1C range depends on your health status and personal factors. Your goal is lowest if you do not have diabetes, and highest if you have diabetes and additional complicating factors. What your A1C should be also considers your individual factors, such as your lifestyle, your treatment and management preferences, and how long you have had diabetes.


A1c Blood Chart Goal Ranges [6, 7]

This A1C normal range chart shows that your HbA1C normal range can vary depending on wh you are.

Situation A1C Goal
Healthy, no prediabetes or diabetes
Less than 5.7%
Less than 5.7% (reverse prediabetes) or 6.4% (prevent type 2 diabetes)
Diabetes with intensive lifestyle change (e.g., weight loss and physical activity)
No more than 6.5%
Diabetes, without additional risk factors
Under 7%
Diabetes, with additional risk factors such as older age, extensive comorbidities, or trouble controlling blood sugar
Under 8%
YOU with your own individual situation
Talk to your doctor!

How to Lower A1C with Lifestyle Changes

You can work towards healthy A1C levels if your test is not in the normal HbA1C range. Healthy lifestyle changes can lower your glycated hemoglobin level if you have prediabetes or your glycosylated hemoglobin test shows that you have diabetes.

Your doctor may have been suggesting for years that you lose weight if you are carrying around extra pounds. There are plenty of reasons to lose weight, and achieving an HbA1C in the normal range is one of them. Each pound that you lose has real effects on your blood sugar levels and health. 

Do you think of restriction and starvation when you think of weight loss? You do not need to. Instead, you might find it easier to lose weight and keep it off with more positive strategies. For example…

  • Eat more. Specifically, eat more non-starchy vegetables because they are low-calorie and filling. Aim to fill half your plate or bowl with vegetables at most meals and snacks.

  • Meet the guidelines. Most Americans should increase their intake of healthy foods such as vegetables, fruit, fish, beans, whole grains, and nuts. As you work to increase those foods, you may end up reducing other, less healthful foods.

  • Eat for fullness. Choose more fiber and lean protein. You will not only get a lower-calorie, more filling meal, but you will have less of a blood sugar swing and stay fuller for longer after your meal.

  • Use a health coaching app. Personalized support, feedback, and tracking food and weight can all help you lose weight.

The other most important step that can lower A1C is to take steps, literally. Exercise increases insulin sensitivity and lowers blood sugar. These guidelines can help you get into an exercise routine.

  • Aim for 30 minutes, most days of the week. You may need to start with much less and work up gradually.

  • You do not have to do 30 minutes at once. You can try 5 or 10-minute increments if that is more convenient for you.

  • Walking, swimming, dancing, and tennis all count. So do gardening, kickboxing, rowing, and aerobics. Anything that gets your heart rate up works.

  • Check with your doctor before starting an exercise program.

  • Consider using a health coaching app for motivation, tracking, reminders, and goal-setting.

Other ways to lower glycated hemoglobin include:

  • Managing stress.

  • Getting adequate sleep.

  • Eating a moderate amount of carbs at most meals and snacks instead of having them all at once.


How to Lower A1C with Medications and Monitoring

Insulin or oral medications for diabetes can get your A1C values down. If your doctor has prescribed one or more medications for you, be sure to take them exactly as prescribed. Your hemoglobin A1C levels may stay high if you skip doses, take them at the wrong times, or take different doses. A digital health coach can help you keep track of your medication use.

Monitoring your blood glucose levels does not directly lower your A1C results, but it can help indirectly as it keeps you on top of your diabetes. When you measure blood glucose one or more times daily, as your healthcare provider suggests, you can identify patterns and figure out what lowers or raises your blood sugar. Since glycated hemoglobin reflects your blood sugar over a few months, your next A1C blood test results may be lower if you have lowered your blood glucose.


When Your A1C Test May Not Be Accurate

A benefit of measuring glycated hemoglobin is that you do not need to fast for it. Also, your A1C value will not change if you exercise before your test. However, some conditions could change your results.[8]

  • Anemia

  • Kidney disease

  • Vitamins E and C supplementation

  • Liver disease

  • High cholesterol

It is always good practice to ask your doctor what your A1C value means.

Your A1C results can tell you about your blood glucose, including if you have prediabetes or diabetes, or how well you are managing diabetes. You might want to ask your doctor for a glycated hemoglobin test, and find out about a personal health coach if you need help lowering your values.


Natalie Stein

Exercise, Fitness & Nutrition Expert | Assistant Professor of Public Health