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7 Reasons Your A1C Might Be High When You’re Not Diabetic

Colleen Magnani, RDN, CDCES

Published in Glucose

7 min read

December 26, 2023
a doctor taking someone's blood
a doctor taking someone's blood

HbA1C, or A1C, is a measurement used to determine your average blood sugar levels over the last three months. The hemoglobin A1C test, which is a key indicator of long-term blood glucose control, is often associated with prediabetes or diabetes diagnosis or treatment.

But 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 without 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 Does The A1C Test Measure?

facts about the a1c test graphic

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 hemoglobin 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?

You might be wondering what is considered a normal A1C range for non-diabetic adults and what's considered to be too high. According to the Centers for Disease Control and Prevention:

a1c percentages graphic
  • A reading under 5.7% is considered to be a normal A1C level
  • An A1C reading between 5.7% and 6.4% may indicate a risk of prediabetes
  • A result of 6.5% or above may be a sign of diabetes

A dangerous level of A1C, which is generally accepted as nine percent or higher, can significantly increase your risk of diabetes-related complications.

As you review your A1C levels with your doctor, it’s good to consider what other variables may be impacting these numbers. While a person’s sex has not been shown to affect A1C levels, there are many factors, such as age, that can influence your A1C levels and cause them to be elevated—and it’s more common than you think. 

Did you know…? A study by the U.S. National Library of Medicine found that adults without a history of diabetes often have A1C levels at 6% or greater

Can You Have High A1C Without Diabetes?

The short answer is yes: it is possible to have high A1C levels without diabetes. Because the A1C test gauges the glucose attached to hemoglobin, any number of factors that influence hemoglobin can impact the results.

Iron deficiency anemia as well as B12 or folate-deficiency anemia may cause A1C to be falsely elevated. If you have high A1C, you’ll want to work closely with a healthcare professional who can help assess your overall health and determine the underlying cause through additional tests and a comprehensive evaluation.

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

7 Reasons Your A1C Is High Even Though You’re Not Diabetic

factors that lead to high a1c levels in non diabetics

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

As we mentioned, 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 a higher A1C reading.

2) You Have Kidney Disease or Liver Disease

a man with back pain

Those who suffer from kidney disease may find it more challenging to rely on the efficacy 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, or 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 in pain

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 Other Abnormal Hemoglobin Variants

Did you know there are multiple 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 elevated A1C reading.

How Can You Lower Your A1C?

tips for lowering 1c levels

As we’ve discussed, there are many reasons why your A1C may be elevated even when your glucose levels are still within a normal, healthy range. Luckily, there are many lifestyle interventions that may help you lower your A1C levels over time, such as:

In addition to these tips, working with a personal nutritionist to implement certain dietary changes is a good way to stay accountable and receive guidance and support as you work to improve your levels. For some people, setting an A1C goal with your doctor is also helpful for tracking and lowering levels over time. 

Learn more about how you can lower your A1C levels here.

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, MS, RDN, LDN

Reviewed by: Heather Davis, MS, RDN, LDN

Heather is a Registered and Licensed Dietitian Nutritionist (RDN, LDN), subject matter expert, and technical writer, with a master's degree in nutrition science from Bastyr University. She has a specialty in neuroendocrinology and has been working in the field of nutrition—including nutrition research, education, medical writing, and clinical integrative and functional nutrition—for over 15 years.

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