An estimated 34 million children and adults in the United States have diabetes, while more than twice that—88 million—are living with prediabetes. What’s more, the American Diabetes Association (ADA) reports that another 7.3 million have diabetes, but don’t know it. One key test—the A1C blood test—is critical to diagnosing and managing the disease. Here’s what the test measures, why it’s important, and how monitoring your glucose levels at home can help. 

What is an A1C test? 

The A1C is a common blood test used to diagnose type 1 and type 2 diabetes as well as prediabetes. If you’re living with diabetes, the test is also used to monitor how well you’re managing your blood sugar, or glucose, levels.

The test measures what percentage of hemoglobin proteins in your blood are coated with sugar (glycated) because when glucose builds up, hemoglobin is what it binds to. Hemoglobin is what gives your blood its red color, and its job is to carry oxygen to all of your organs and tissues. 

Since your red blood cells live for about 3 months, the A1C test shows the average level of glucose in your blood from the past 2-3 months. In general, the higher your A1C levels, the poorer your blood sugar control and the higher your risk of diabetes complications. 

In a way, the A1C test captures the bigger picture, like a basketball player’s points-per-game average for the season. It gives you a snapshot into the athlete’s overall success—something that can’t be seen in a single game or from a single day’s blood test results.

What the A1C numbers mean (and what a normal range is)

A1C test results will come back as a percentage—the percent of your red blood cells that have sugar-coated hemoglobin. The higher the percentage, the greater your risk of developing diabetes complications. In addition to helping diagnose diabetes and prediabetes, the test will also give you a baseline A1C level. If you have prediabetes or diabetes, you’ll be tested regularly and can compare those results to your baseline to see how your treatment plan is going. Here’s what your numbers could look like and what they mean:

If your levels are below 5.7%, that is considered normal. If you land between 5.7% and 6.5%, you fall into the prediabetic category and you’re at a higher risk of developing diabetes. If your test results show you’re above 6.5%, you’re considered in the diabetic range. To confirm a diabetes diagnosis, your healthcare provider will likely look at the results of two blood tests given on different days. The goal A1C for most patients with diabetes is 7% or less, though individual goals may vary depending on the specific circumstances.

Something to keep in mind is that certain factors like pregnancy, kidney and liver disease, certain medications with opioids, some HIV medications, recent or heavy blood loss, or conditions like anemia can all interfere with the accuracy of the A1C test results. These could all influence your A1C goal and are things you can discuss with your healthcare provider ahead of time.

A1IC targets can also change over time as your age or your health condition changes. Generally younger people have a lower A1C goal in order to reduce diabetes-related complications, whereas older people or those with other comorbidities have a higher A1C goal This is why it’s important to work with your doctor to set your own individual A1C goal.

What’s the difference between the A1C test and home glucose monitoring?

If you’re prediabetic or diabetic, you’ll work with your healthcare provider to come up with a treatment plan. A part of your home treatment plan will likely include self-monitoring, which you can do with a blood glucose meter or other device. This will tell you your blood sugar levels at the exact time you do the test—either in milligrams of sugar per deciliter (mg/dL) or millimoles of sugar per liter (mmol/L). 

Blood sugar goes up and down during the day and night, and factors like eating, exercise, or stress, can all affect your blood sugar. So you might see some variability throughout the day in your numbers. To come back to the basketball analogy, these tests can be likened to a single game’s stats and can reveal the daily nuance that the A1C test can’t. 

On the other hand, because the A1C test measures the average blood glucose over the past three months, it provides a good idea of overall glycemic control over time. As we mentioned earlier, it captures the bigger picture. It also doesn't require fasting, like some blood glucose tests, so it can be given at any time.

The in-the-moment precision of self-monitoring can be helpful when it comes to making choices about your diet and exercise throughout the day. It can also help you keep tabs on your A1C target. For example, if your A1C goal is below 7%—a common target for people with diabetes—you should aim for blood sugar below 154 mg/dL (8.6 mmol/L) on average. The ADA offers a simple A1C calculator where you can easily convert between A1C and eAG.

How often should I get an A1C test?

There’s no one-size-fits-all when it comes to how often you should get tested. The frequency will be determined by your healthcare provider and will depend on a few factors unique to you including your age as well as if you’re on any current diabetes treatment plan with certain goals. 

In general, however, if you have prediabetes, the Mayo Clinic recommends getting tested once a year. If you have diabetes, and if your blood sugar level is consistently within your target range and you don’t use insulin, twice a year is recommended. If your blood sugar levels have been out of your target range and you are using insulin, your doctor might recommend up to four times per year. Additionally, if your diabetes treatment plan changes or you begin taking a new diabetes medication, that could also increase the frequency of A1C testing. You can work with your healthcare provider to decide what works best. 

Whether you're navigating medications for a recent diagnosis or are looking to learn more about diabetes prevention, we know it can be a lot to sort through. That’s why we’re here to help every step of the way. 

From glucose monitors to test strips to medications, our team of patient care pharmacists at Alto is available to chat whenever questions come up. Feel free to reach out any time via in-app secure messaging.

This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have regarding a medical condition.