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a doctor taking someone's blood
a doctor taking someone's blood

As we explained in our guide to understanding A1C, HbA1C, or A1C, is a measurement used to determine your average blood sugar levels over the last three months. 

While high blood sugar may be a risk factor for diabetes mellitus, high A1C is not exclusively seen in those with the health condition. In fact, people can have a high A1C even if they don’t have a history of diabetes

Want to find out what other factors can lead to high A1C? Let’s explore what the A1C test measures, what lifestyle factors can lead to elevated levels, and what you can do if your A1C is high.

What is the A1C Test Measuring?

Any sugar that enters your bloodstream attaches itself to the hemoglobin on your red blood cells. Hemoglobin is the oxygen-rich protein found in red blood cells. It’s oxygen-rich because it’s in charge of moving oxygen from your lungs to other tissues in the body. 

Glucose attaches to the hemoglobin protein in the blood, and the amount of this glycated hemoglobin can be measured by a hemoglobin A1C test. This provides a good proxy of how much glucose on average was present in your bloodstream over a two to three-month period. 

So what happens when A1C is too high? Over time, high A1C levels may lead to impaired fasting glucose, high blood pressure, obesity, and an increased risk of type 2 diabetes and cardiovascular diseases.

A higher A1C percentage may also indicate a higher risk of diabetes. However, there can be several reasons for a spike in blood sugar levels, and it’s a good idea to know what’s causing yours.

What Are Normal A1C Levels?

Before we dive into the different reasons you A1C levels might be elevated, let's first take a look at what is considered a normal A1C range and what's considered to be too high.

a1c percentages graphic

According to the Centers for Disease Control and Prevention, a reading of under 5.7 percent is considered to be a normal A1C level. A reading between 5.7 percent and 6.4 percent may indicate a risk of prediabetes, while A1C levels above 6.5 percent can be a sign of diabetes

As you review your A1C levels with your doctor, it’s good to consider what other variables may be impacting these numbers. For example, the U.S. National Library of Medicine found that adults without a history of diabetes often have A1C levels at six percent or greater. 

However, there are many factors that can influence your A1C levels and cause them to remain elevated.

Can You Have High A1C Without Diabetes?

The short answer is yes: it is possible to have high A1C levels without diabetes. Because there are a number of lifestyle factors that can affect your hemoglobin, you’ll want to work closely with your healthcare provider to determine what is causing your high A1C level.

From there, you may be able to work with a personal nutritionist to implement certain dietary and lifestyle changes that can help you improve your level. For some people, setting an A1C goal with your doctor may help you track and lower your levels over time.

facts about the a1c test graphic

Now that you’re familiar with the A1C test and normal A1C levels, let’s explore seven reasons why A1C may be high in people who do not have diabetes.

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7 Reasons Your A1C Results Came Back High Even Though You’re Not Diabetic

From vitamin deficiency to certain medical conditions, there are many factors that might lead to a high A1C result. Here are seven of the most common reasons.

1) You Have Anemia

a girl looking tired

Any interference with your red blood cells or changes in hemoglobin can falsely skew the results of an A1C test. Anemia, which is a condition usually caused by a lack of iron or deficiencies in vitamins B12 or folate, is a good example. 

According to one study, iron-deficient individuals without diabetes had higher A1C more frequently. When classified by gender, the study found that iron-deficient women were more likely to have higher levels of A1C.

2) You Have Kidney Disease or Liver Disease

someone holding their waist in pain

Those who suffer from kidney disease may find it more challenging to rely on the efficiency of A1C tests. Kidney disease can cause complications like anemia, malnutrition, and even kidney failure. 

These factors may affect the results of an A1C test. In the case of liver disease, the A1C test may also not be an accurate predictor of glycemic control due to factors such as anemia, which can affect your red blood cells.

3) Some Medications Can Cause High A1C Levels

Several different medications may interfere with A1C test results. Some can even cause errors in readings or bring up inaccurate results. For example, some anti-retroviral drugs and even over-the-counter drugs like aspirin can cause your A1C levels to appear inflated or inaccurate.

The types of medicines that can lead to false A1C levels include drugs that cause hemolysis, such as dapsone, may interfere with glycation. This study also found evidence that extremely high doses of antioxidants may also affect glycation.

Research suggests that chronic or overuse of certain medications is what may skew the results of an A1C test to be high. However, low doses of medications like aspirin have also been found to cause A1C levels to skew low and lead to low A1C levels.

4) You Have Disorders Related to the Spleen

a girl holding her stomach and feeling sick

Spleen disorders, like sickle cell or asplenia, may also affect your A1C tests. Some research has shown that A1C levels can appear elevated following a splenectomy, or spleen removal procedure.

These disorders, which are known as hemoglobinopathies, have been shown to affect the accuracy of A1C tests when a patient inherits a hemoglobin variant. If you suffer from any of these conditions, you may start to see false highs in your test results.

5) You Have Low Thyroid Hormone Levels

Thyroid hormones regulate your metabolic rate and the rate at which your body burns calories. The amount of thyroid hormones in the bloodstream can affect your A1C level.

This can potentially cause the reading to fluctuate or give you false results. For example, hypothyroidism, or low thyroid hormone levels, has been shown to lead to an elevated level of A1C.

6) You Have an Abnormal Hemoglobin Variant

a doctor testing someone's blood

Did you know there are a number of variants of hemoglobin? The most common type is hemoglobin A. It’s not common to know your type, but if you’re wondering what’s leading to elevated A1C levels, you may want to check yours with your doctor. 

Type HbAS, which is most commonly observed in people of African descent, is an inherited blood disorder that can lead to false A1C readings that may not accurately reflect your glycemic control. 

To find out what types you have, you might talk to your doctor about considering a blood test called the hemoglobin electrophoresis test

7) Your Age

Early studies looking at the impact of age on A1C failed to demonstrate an association due to failures in methodology. However, newer studies like this one studying the effects of age on A1C have found a link between age and higher A1C in individuals with normal glucose and without diabetes.

Researchers believe that changes in the rate of glycation associated with aging may be responsible for this altered A1C reading.

Supporting Healthy A1C Levels

a doctor testing someone's heartbeat

As we’ve discussed, there are many reasons why your A1C may be elevated even when your glucose levels are still within a healthy range. 

Since many of those reasons are related to health conditions like anemia, altered thyroid function, and organ (liver, kidney, spleen) function, it's important to work with your qualified healthcare provider in exploring any potential deeper issues.

Implementing healthy lifestyle habits like eating a balanced diet, getting regular exercise, getting adequate sleep, and managing your stress are other ways to improve your glucose response and overall well being. For more on A1C levels, visit our Instagram.

Engage with Your Blood Glucose Levels with Nutrisense

Your blood sugar levels can significantly impact how your body feels and functions. That’s why stable blood glucose levels can be an important factor in supporting overall wellbeing.

With Nutrisense, you’ll be able to track your blood glucose levels over time using a CGM, so you can make lifestyle choices that support healthy living.

When you join the Nutrisense CGM program, our team of credentialed dietitians and nutritionists are available for additional support and guidance to help you reach your goals.

Ready to take the first step? Start with our quiz to see how Nutrisense can support your health.

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Heather Davis

Reviewed by: Heather Davis MS, RDN, LDN

Heather has worked in healthcare and nutrition for over 15 years, with bachelor's degrees in Microbiology and Philosophy and a master's degree in Nutrition Science. Her professional background includes nutrition and diabetes research, nutrition education, medical writing, and extensive clinical work in a functional neuroendocrine specialty practice.