Tens of millions in the United States are at risk of diabetes, but how do you know if you’re one of them? The A1C test can tell you if you’re on track to developing diabetes so you can take steps to avoid this potentially deadly condition. If you already have diabetes or prediabetes, the A1C tests can help guide your treatment plan and reduce your risk of diabetes complications.
This guide will cover everything you need to know about the A1C test, including when you need it and how to understand the results. We’ll also go over the basics of diabetes care and what you can do to reduce your risk.
What Is an A1C Test?
The A1C test is a simple blood test used to diagnose and monitor diabetes. It can estimate the glucose levels in a person’s bloodstream over the last two to three months. The A1C test is also known as the hemoglobin A1C (HbA1c) or glycated hemoglobin test because it measures the percentage of hemoglobin proteins in your blood that are sugar-coated or “glycated.”
When Do Doctors Use an A1C Test?
An A1C test has three purposes:
- Prediagnosing diabetes: Nearly 100 million Americans have what is sometimes called “prediabetes,” which means higher-than-average blood glucose levels that don’t meet the diagnostic criteria for diabetes. Doctors may prescribe an A1C blood test for people based on risk factors like obesity or age.
- Confirming a type 1 or type 2 diabetes diagnosis: There are several blood tests used to diagnose diabetes, but A1C is the most common. A doctor will typically administer two blood tests on separate days. They may choose two A1C tests or a combination of an A1C test and other diabetes tests, like a random blood sugar or fasting test.
- Monitoring a patient’s diabetes management plan: A1C test results provide a reference for a patient’s average blood sugar levels that the health care team can use as a baseline for a treatment plan. An A1C test is a tool to manage diabetes because regular readings of estimated average glucose can show progress toward treatment goals.
Check out our Free A1C Calculator
Taking the A1C Test: What to Expect
The A1C test is a simple blood test you can take at any doctor’s office. You don’t need to fast or refrain from drinking fluids before you take it. A medical professional will draw blood from your arm using a needle. Alternatively, they may prick your fingertip with a lancet.
If you are seeking a diabetes diagnosis, the blood sample will be sent to a lab for analysis, so you may not get your results for a few days. However, if it’s a blood glucose test for monitoring purposes, it’s sometimes possible to get same-day results from your doctor.
Understanding A1C Test Results
As we already mentioned, the A1C test measures the estimated average glucose in the bloodstream by checking the amount of glycosylated—or sugar-coated— hemoglobin in a blood sample. Hemoglobin is a protein found inside red blood cells that carries oxygen throughout the body.
A1C is an indicator of blood sugar control. A1C test results are expressed as a percentage representing the percent of glycosylated hemoglobin proteins in the average red blood cell.
Here’s a quick overview of what each A1C score means:
- Under 5.7 percent: If your average blood sugar levels are below this percent, you are in the normal range for a healthy adult.
- 5.7 to 6.5 percent: Blood glucose levels in this range signify prediabetes. If your test results show a higher-than-average blood sugar level, you need to reduce your weight and other risk factors for diabetes.
- Greater than 6.5 percent: If two lab tests administered on separate days show an A1C of 6.5 percent or higher, you have diabetes, and you need to begin a treatment plan to reduce your blood sugar that typically involves diabetes medication, exercise, dietary changes, etc
- Greater than 9 percent: If blood samples show blood glucose levels greater than 9 or 10 percent A1C, a person is in extreme danger of severe and possibly deadly complications, such as cardiovascular disease, digestive and kidney diseases, blindness, and limb amputation.
A1C, eAG, and Diabetes Monitoring
A1C is sometimes referred to as eAG or “estimated average glucose.”Typically, eAG is expressed in units of mg/dl, matching the unit on a blood glucose meter. However, this figure will likely be somewhat higher than the average that displays on blood glucose meters diabetes patients use to monitor their blood sugar levels daily.
The A1C or eAG percentage is the estimated average blood glucose level over two or three months, whereas your blood glucose meter shows an average of daily readings. Most people take their blood glucose at a low level (ex., When they first wake up or before meals).
The eAG/A1C value provides a more reliable representation of a person’s blood sugar over 24 hours. The following chart from the American Diabetes Association shows how A1C (expressed as a percentage) converts to eAG in mg/dl and vice versa.
How Often Do You Need an HbA1C Test?
The recommended frequency of testing varies depending on your diagnosis.
- Normal range: If you’ve never been diagnosed with diabetes or prediabetes, you should begin routine diabetes screening at age 45 and test every three years after that.
- Prediabetes: Those with prediabetes should get tested every one or two years or as their doctor recommends. If you’ve been diagnosed with prediabetes but show no symptoms, you should probably get a second confirmation test.
- People with diabetes: After a diabetes diagnosis, you should get an A1C test twice a year to ensure you progress toward your treatment goals.
Factors That Can Affect Your A1C Test Results
Genetics, medical conditions, and pharmaceuticals can affect blood glucose tests raising or lowering your A1C score:
- If you are of African, Middle-Eastern, or Southeast Asian descent, you might have a hemoglobin variant associated with sickle-cell anemia or thalassemia.
- Kidney failure, severe anemia, and liver disease
- Opioids and certain HIV/AIDs medications
- Early or late-stage pregnancy
- Blood loss or blood transfusions
Your doctor should review your medical history before taking the A1C test and ask about most of these conditions. If they don’t, be sure to inform them if any of these factors apply.
Diabetes Care and Management
To properly manage your diabetes, avoid complications, and keep your A1C percentage in the target range, health experts recommend the following:
- Eat a healthy, low-carb diet
- Avoid smoking
- Manage stress, blood pressure, and cholesterol
- Get routine checkups and eye exams
- Keep vaccinations up to date
The A1C test, sometimes known as the hemoglobin A1C (HbA1c) test, is a powerful tool for diagnosing and monitoring diabetes. Expressed as a percentage, an A1C score signifies the percentage of hemoglobin proteins in your bloodstream that are covered in sugar.
An A1C score higher than 5.7 percent indicates prediabetes. A score higher than 6.5 means you have diabetes. While diabetes is a manageable condition, it should be taken seriously. Poorly managed diabetes can lead to a shorter life expectancy and complications such as limb amputation and blindness.