An A1C blood test measures average blood sugar levels over the past 2–3 months.

The A1C test, which some people may also call the hemoglobin A1C, HbA1C, glycated hemoglobin, or glycohemoglobin test, measures the amount of sugar attached to hemoglobin in the blood. A doctor can use it to monitor diabetes and as a diagnostic tool for the condition.

If a person’s A1C levels are too high, it suggests their blood sugar levels are too high. When blood sugar levels are too high for a long period of time, this can result in health complications.

By incorporating lifestyle behaviors, such as regular exercise, a varied eating plan, and following their diabetes treatment plan, a person may lower their blood sugar. This will lower their A1C percentage and reduce the likelihood of potential health problems.

In this article, we will discuss why it is important to maintain healthy A1C levels.

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The A1C test refers to a blood test that measures a person’s average blood glucose levels over the past 3 months. It shows the average percentage of sugar-bound hemoglobin in a blood sample.

A doctor can use the A1C test to not only help diagnose diabetes but also to determine how well a person with diabetes is managing the condition.

When glucose enters the blood, it binds to a red blood cell (RBC) protein called hemoglobin. This protein is responsible for carrying oxygen throughout the body. The resulting compound is known as glycosylated hemoglobin.

Doctors call the test an A1C test because roughly 95–98% of the hemoglobin present in the body is type A1. Type A1 hemoglobin has subtypes, such as A1C. As this is the most abundant subtype, a doctor can use it as a good marker for glucose control.

How does a doctor calculate A1C?

The A1C test estimates the average blood glucose level over the past 3 months. The test can measure this by identifying the percentage of glycosylated hemoglobin in the blood. The test measures this period because RBCs typically live for about 3 months.

As such, this timeframe can reflect how much sugar the RBCs had exposure to during that period.

If more glucose is present in the blood, that means more is available to attach to hemoglobin. A high percentage of glycosylated hemoglobin indicates a person had high blood sugar during the past 3 months. This can suggest that the individual is not effectively managing their blood sugar.

Many studies have shown that lowering A1C levels can help slow the progression of diabetes and reduce the risk of complications — such as nerve damage and cardiovascular disease — in both type 1 and type 2 diabetes.

When it comes to an A1C target range, there is no one-size-fits-all solution. Many factors, including the type of diabetes and general health, can impact an A1C goal. A person can discuss a suitable target with their diabetes healthcare team.

The American Diabetes Association (ADA) notes that the goal for most adults living with diabetes is an A1C of less than 7%. Many strategies, such as physical activity, diet, and medication, can help manage blood glucose levels and, therefore, also A1C levels.

Exercise and lifestyle tips to help lower A1C levels include:

  • Physical activity: Current guidelines recommend that adults perform a minimum of 150 minutes of moderate physical exercise each week. People who use insulin or have special considerations should contact their doctor about a suitable exercise plan.
  • Routine activities: Housework, gardening, and other routine activities can all help keep a person moving.
  • Monitoring blood glucose: This is crucial to ensure a person meets their targets and makes any necessary changes.
  • Following the treatment plan: This includes the use of medications and lifestyle therapies.
  • Weight management: The person may consider working with a healthcare professional to set realistic and achievable weight loss goals.
  • Tracking progress: This is useful for self-motivation, monitoring changes, and identifying which strategies work for a person.
  • Getting others involved: Lifestyle changes are often easier to adopt if other people can encourage and monitor progress.

Everyone, especially people with diabetes, can benefit from a healthful diet that includes plenty of fresh fruit and vegetables and whole foods and is low in sugar, salt, and fat.

Monitoring carbohydrate intake can help a person manage their glucose levels.

General diet tips to lower A1C levels include:

  • being mindful of portion sizes
  • eating regularly, every 3–5 hours
  • eating similar-sized portions at meals and snacks
  • planning meals ahead of time
  • keeping a journal of food, medication, and exercise
  • spreading out carbohydrate-rich foods throughout the day
  • choosing less-processed or whole foods such as whole grains, fruits, vegetables, legumes, and nuts
  • eating a balanced diet complete with healthy proteins, fats, and carbohydrates
  • seeking out the help of a registered dietitian

A healthcare professional will advise each person on their dietary needs, including the number of carbs they should consume. This will depend on individual factors, including the person’s exercise levels and treatment plan.

Nutrition plays an essential role in managing blood sugar levels. Following a suitable eating plan can help a person keep their blood sugar and A1C levels in a healthy range.

Creating a meal plan can be a useful tool to help a person manage their blood sugar. A dietitian can also help with recommending an eating plan. Additionally, people can try following the ADA’s Diabetes Plate Method.

For people living with diabetes, some important trends to incorporate into an eating plan include:

  • eating sufficient fruits and vegetables
  • eating lean protein
  • choosing foods with less added sugar
  • limiting trans fats
  • eating fewer processed foods

Learn more about food to help lower and control blood sugar here.

A1C test results appear as a percentage. A higher A1C level means a greater risk of diabetes and its complications.

Physicians may also refer to average glucose, or eAG, when they talk about A1C levels. The eAG corresponds to A1C, but it appears as milligrams per deciliter (mg/dl), like blood sugar.

Both A1C results and eAG refer to a person’s average 3-month blood glucose levels. People can use a simple calculator to help them convert their results from one measurement to the other.

A1C valueeAG valueADA diagnosis
5.6% or less114 mg/dl or lessNormal
5.7–6.4%117–137 mg/dlPrediabetes
6.5% or more140 mg/dlDiabetes

A person with prediabetes has a good chance of reversing their high blood sugar levels and preventing diabetes from developing.

Read about more tips and strategies for managing prediabetes here.

A1C level recommendations vary between individuals. People with more advanced diabetes will have higher A1C targets than healthy adults without diabetes. Factors such as life expectancy, treatment response, and medical history also have an impact.

A1C valueeAG valueADA recommended goal for:
5.6% or below114 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 nonpregnant 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

A1C levels are a measure of blood glucose over 3 months. A doctor can use this measurement to monitor and diagnose diabetes.

An A1C level of 6.5% or more indicates that a person may have diabetes.

Keeping the A1C level within a healthy range can help to reduce the likelihood of complications.

Strategies to manage blood sugar and A1C can include a varied eating plan, regular exercise, and following a diabetes treatment plan.