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Understanding A1C numbers: How to use your results for better blood sugar

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Julie Cunningham, MPH, RDN, CDCES, IBCLC

If you live with diabetes, you've probably become intimately familiar with the term "A1C" — but you may not know why you need to get your blood drawn for this lab test every two to three months. You may also wonder how understanding A1C numbers can help you better manage your diabetes. We've got you covered!

Here's what you should know about the A1C test, why you need to keep an eye on your numbers, and what your results mean for your diabetes management and your health.

What is an A1C?

A1C is a shortened version of the phrase "hemoglobin A1C." Hemoglobin is a medical term that refers to "red blood cells." The A1C portion tells scientists that sugar is attached to the red blood cells. So when you get your A1C checked, you're really getting a test to see what percentage of your red blood cells have sugar attached to them.

Every day, your body makes new red blood cells. And every day, some of your old red blood cells die. This is a normal process — each red blood cell lives inside your body for about 12 weeks. As your red blood cells circulate throughout your body, some of them pick up and carry sugar with them. The higher your blood sugar levels are, the more sugar your red blood cells may pick up and carry with them.

Here's a fun way of thinking of it: Red blood cells are kind of shaped like donuts, so red blood cells with sugar attached can be thought of as glazed donuts. The higher your blood sugar levels, the more "glazed donuts" are in your system.

Understanding A1C numbers

When blood sugar increases, so do A1C numbers. As someone living with diabetes, you'll want to keep track of your numbers, but they can also be helpful to those without the condition! Alongside blood sugar tests, A1C tests can be used to diagnose diabetes and prediabetes.

These are the American Diabetes Association (ADA) official guidelines for the diagnosis of diabetes using A1C levels:

  • Normal A1C: less than 5.7%.
  • Prediabetes: 5.7% to 6.4%.
  • Diabetes: 6.5% or higher.

Using A1C to determine estimated average glucose (eAG)

In addition to determining a diagnosis of diabetes or prediabetes, A1C numbers can be used to determine the estimated average glucose (eAG), which details the amount of sugar in a person's bloodstream over the past two to three months. An individual's eAG can be used to better understand how certain choices affect blood sugar because it tracks glucose levels over time (as opposed to right before and after meals). In this case, the higher the A1C, the higher the eAG.

According to MedlinePlus, a normal eAG value is between 70 mg/dl and 126 mg/dl (which translates to an A1C reading of 4% to 6%). People living with diabetes should aim for an eAG less than 154 mg/dl (and an A1C of less than 7%) to lower their risk for diabetes complications.

This graph illustrates a breakdown of A1C levels as well as their corresponding eAG, according to the ADA:

A1C eAG
% mg/dl mmol/l
6 126 7.0
6.5 140 7.8
7 154 8.6
7.5 169 9.4
8 183 10.1
8.5 197 10.9
9 212 11.8
9.5 226 12.6
10 240 13.4

Using A1C numbers to better manage diabetes

If you've already been diagnosed with diabetes, you can use your A1C to help prevent complications. In fact, you may already know these goals for people with diabetes, as suggested by the ADA:

  • Fasting blood glucose: 80-130 milligrams per deciliter.
  • Post-meal blood glucose: less than 180 milligrams per deciliter.
  • A1C: less than 7%.

Your A1C number can help you understand whether you've been in your desired range most of the time, or if you need to make adjustments to the three big factors that affect your blood sugar: medications, food, and physical activity.

Unless you check your blood sugar multiple times a day, it may be hard to notice changes in your blood sugar levels due to small lifestyle tweaks (like walking an extra five minutes or skipping the sugar in your coffee). But small daily changes may show up as significant changes in your A1C. Accordingly, an A1C test can be a big motivator for some people!

Understanding the A1C goal for people with diabetes

Curious why the A1C goal for people with diabetes is less than 7% when a "normal" A1C is under 5.7%? A report published in The Review of Diabetic Studies showed that when A1C stays under 7%, complications related to diabetes (such as loss of vision and loss of kidney function) are minimal.

At the same time, extremely tight control of your blood sugar might result in some unwanted issues, like hypoglycemia. So, an A1C of less than 7 seems to be the sweet spot where most people with diabetes can avoid complications from both highs and lows.

Want to know more about better blood sugar management? Check out the library of articles on Health Insights to learn what factors affect blood glucose levels.

Julie Cunningham, MPH, RDN, CDCES, IBCLC

Julie Cunningham is a Registered Dietitian Nutritionist and a Certified Diabetes Care and Education Specialist. Julie provides online nutrition programs for people who want to end their struggle with diabetes. She can be found at juliecunninghamrd.com and at TameType2.

FB: https://www.facebook.com/juliecnutr/ LinkedIn: https://www.linkedin.com/in/julie-cunningham-a042092a/ Insta: https://www.instagram.com/juliecunninghamrd/

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