The A1C test is a blood test that measures the body’s average blood sugar levels over the past 3 months. The test can help doctors identify prediabetes, diagnose diabetes, and monitor the effectiveness of diabetes treatments.

The A1C test, also known as the hemoglobin A1C, HbA1C, glycated hemoglobin, or glycohemoglobin test, measures the amount of sugar attached to hemoglobin in the blood.

Hemoglobin is a protein present in red blood cells (RBCs), and sugar naturally attaches to it. However, as people with higher blood sugar levels have more sugar-coated hemoglobin, it is a useful test to help check and monitor diabetes status.

As higher A1C levels are often associated with diabetes complications, it is important to reach and maintain target A1C results. An individual’s personal A1C goal will depend on many factors, including age and any other medical conditions. Although it is an important tool for managing diabetes, testing A1C levels does not replace other strategies, such as regular blood sugar testing at home.

A person can work toward lowering and maintaining their A1C level by following their treatment plan, getting regular physical exercise, and taking steps to lose weight, if the doctor has advised doing so.

In this article, we discuss healthy and concerning A1C levels, the possible complications of high levels, and strategies to reduce A1C levels.

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A1C test results represent how well the body is maintaining blood glucose levels by showing the average percentage of sugar-bound hemoglobin in a blood sample. A higher A1C level suggests a higher risk of diabetes and its complications.

When discussing A1C levels, a doctor may also refer to estimated average glucose, or eAG. The eAG corresponds to A1C, but it appears as milligrams per deciliter (mg/dl), as with blood sugar. Both A1C and eAG refer to a person’s average 3-month blood glucose levels.

A1C valueeAG valuePotential diagnosis
5.6% or less117 mg/dl or lessNormal
5.7–6.4%117–137 mg/dlPrediabetes
6.5% or more137 mg/dlDiabetes

However, A1C level recommendations can vary among individuals due to a number of factors. What may be high for one person might be within range for another person.

For example, people with more advanced diabetes will have higher A1C targets than those without diabetes. Various underlying conditions, including blood disorders, can also have an effect, as can potentially modifiable factors, such as stress, medications, and lifestyle changes.

A1C valueeAG valuePotential targets for:
5.6% or below117 mg/dl or belowhealthy adults without diabetes
6.5%140 mg/dlpeople with short-term diabetes, managed type 2 diabetes, no cardiovascular disease, long life expectancy
7% or less154 mg/dl or lessmost non-pregnant adults with diabetes
8% or less183 mg/dl or lesspeople with long-standing or severe diabetes, limited life expectancy, extensive additional health complications, or poor treatment response

A person with an A1C level indicating prediabetes may wish to consider making lifestyle changes, such as adopting a well-balanced diet and staying active, to help manage or even reverse the condition before it progresses to type 2 diabetes.

If a person has a higher A1C level, suggesting diabetes, it is advisable for them to contact a doctor. The doctor will be able to run further diagnostic tests to confirm the person’s diabetes status.

The A1C goal for most people with diabetes is 7% or less. However, personal targets can vary, and a diabetes care team may consider other factors to help a person set their own individual goals.

If a person with diabetes has an A1C test result that is much higher than their set target, a doctor can help advise lifestyle and medication changes to lower their A1C level.

The A1C test is a blood test that measures a person’s average blood sugar levels over the past 3 months. In particular, it measures the percentage of hemoglobin in the blood with an attached molecule of glucose.

When glucose attaches to hemoglobin, experts refer to the resulting compound as glycosylated hemoglobin. The name of the test derives from the fact that about 95–98% of the hemoglobin present in the body is type A1. Type A1 hemoglobin has subtypes, including A1C. As this is the most abundant subtype, it is a good marker for glucose control.

The test uses a 3-month average because RBCs typically live for about 3 months. Therefore, this timeframe reflects the sugar exposure to the cells over that time. The test does not require any specific preparations, so a person does not need to fast prior to the test, and a doctor can perform it at any time of the day.

The A1C test estimates the average blood sugar level over the past 3 months. The test is able to measure this by identifying the percentage of glycosylated hemoglobin in the blood.

If there is more glucose present in the blood, more glucose is available to attach to hemoglobin. Therefore, if a person has a high percentage of glycosylated hemoglobin, it indicates that they have had high blood sugar for an extended period.

A high A1C level can be concerning, as it may indicate that an individual has a higher risk of diabetes complications. For those without a diabetes diagnosis, it suggests that, without interventions, they may develop the condition. For individuals living with diabetes, it may indicate that their current treatment plan is not effective and that they should contact a doctor.

Potential complications that can result from high blood sugar levels include:

  • kidney disease
  • eye disease
  • stroke and cardiovascular disease
  • metabolic syndrome
  • neuropathy

As many factors can affect a suitable A1C range, there is no standardized approach when it comes to setting A1C goals. A diabetes healthcare team can help provide an individual with a target level that accounts for various factors, including the current A1C value and the date of the next test.

If the test result is already within a healthy range, the goal should be to maintain that. However, if a person enters the higher ranges, a doctor can suggest changes to their goals and treatment plans. They can help the person determine a reasonable target and the best strategy to achieve that goal.

If a person’s A1C level is above their target, a doctor can provide suggestions to help lower it and reduce the risk of potential complications. A person should discuss any drastic lifestyle changes with a doctor before making them. Suggestions to help lower A1C levels may include:

  • Reviewing medication: This may involve changing to a different medication or increasing the current dosage. It is also important to ensure that a person is correctly following their treatment plan.
  • Regular physical exercise: Physical activity is good for general health, and as the body requires glucose to exercise, it can be a beneficial way to lower blood sugar levels.
  • Healthy diet: A balanced and nutritious diet can help with managing sugar levels. Additionally, it can help people achieve any weight loss goals.
  • Stopping smoking: Smoking has many potential health risks, and quitting smoking may also help improve blood flow.
  • Diabetes education courses: Some people may benefit from attending educational courses and learning strategies to manage their sugar levels more effectively.

An A1C test is a diagnostic tool that measures blood sugar levels over the last 3 months. It can help doctors identify people at risk of developing diabetes and monitor the effectiveness of treatments in those living with the condition.

It measures the percentage of hemoglobin in red blood cells that has an attached glucose molecule. If a person has high blood sugar, more glucose is available to attach to hemoglobin. This means that individuals with high blood sugar will have a higher percentage of glycosylated hemoglobin and an increased risk of potential complications.

People can work toward lowering their A1C levels by implementing different strategies, such as following their current treatment plan, getting regular exercise, and taking steps to lose weight, if necessary.