What is the A1C test for diabetes?

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The A1C test is a test that measures a person's average blood glucose level over the past 2 to 3 months. Hemoglobin is the part of a red blood cell that carries oxygen to the cells and sometimes joins with the glucose in the bloodstream. Also called hemoglobin A1C or glycosylated hemoglobin, the test shows the amount of glucose that sticks to the red blood cell, which is proportional to the amount of glucose in the blood.

Hemoglobin A1C (A1C) test results reflect average glycemia over several months and correlate with mean plasma glucose levels. An estimated average glucose (eAG) is directly related to A1C and also provides an individual with an estimate of average blood glucose over a period of time, but it uses the same values and units that are observed when using a glucose meter or recording a fasting glucose value on a lab report.

If you have diabetes, at least every 3 to 6 months, your doctor should order an A1C test, which may be reported as eAG. It is a different number than your blood glucose checks. The result will tell you your average blood glucose for the past 2 to 3 months.

Although the A1C test is an important tool, it can't replace daily self-testing of blood glucose for those who need it. A1C tests don't measure your day-to-day control. You can't adjust your insulin on the basis of your A1C tests. That's why your blood sugar checks and your log of results are so important to staying in effective control.

Stacy Wiegman, PharmD
Pharmacy Specialist

The A1C diabetes test is a way to get an average of how well your blood sugar has been controlled for the past three months. A good score on the A1C test depends on whether you’ve been diagnosed with diabetes. For those who do not have diabetes, a score of less than 5.7 percent is considered normal, while 5.7 percent to 6.4 percent indicates prediabetes and 6.5 percent or higher means you have diabetes. If you already have diabetes, a score of 7 percent or lower is desired. You and your doctor can decide what score is best for you.

Dr. Joe M. Llenos, MD
Family Practitioner

A good score on the A1C diabetes test is below 7 for an adult and below 8 for elderly patients. Watch this video to hear Joe Llenos, MD, from West Valley Medical Group - Caldwell, explain the A1C diabetes test.

Amy Campbell
Endocrinologist

For most people with diabetes, the A1C goal is less than 7 percent in order to help avoid complications. However, the A1C goal may be modified based on the presence of certain complications, cognitive status and life expectancy. Also, people who have hypoglycemia unawareness (the inability to feel symptoms of low blood glucose) may benefit from a higher A1C goal for safety reasons. Make sure you talk to your healthcare provider about what you own A1C goal should be.

The A1C test measures how much glucose is attached to the red blood cells in your body. Since these cells are replaced every 90 days, the result of the A1C test shows how good your blood sugars have been over the past three months. There has been much research recently suggesting that for diabetes patients, an A1C level of 6.5 is a magic number below which many of the complications of diabetes are less severe.

The high A1C is evidence that you may need to do better in diet and exercise or that your medication regimen needs to be adjusted, despite what your meter is telling you.

There are three lessons to be learned here:

  1. You need to test your blood at different times of the day, paying attention to how your body reacts to various foods, exercise, illness and stress, and—most importantly—to the medications you are taking.
  2. Regardless of what your meter tells you, it is no substitute for that A1C blood test every three months.
  3. There’s a device called a Continuous Blood Glucose Monitor that measures blood sugar every five minutes for a week. If you keep a log of your daily activities—“ate cottage cheese at 8 a.m., walked a mile at 10 a.m.”—that can be correlated to the monitor reading and tell you exactly what was happening to your blood sugar at each activity.

Hemoglobin A1c is a test used to tell you your average blood sugar over time. In this video, Ronald Tamler, MD, clinical director of the Mount Sinai Diabetes Center, explains the test and what its results mean.

Mrs. Marjorie Nolan Cohn
Nutrition & Dietetics Specialist

The A1C test is used to diagnose diabetes. The higher your A1C level, the higher your risk of diabetes complications. An A1C level of 6.5 percent or higher on two separate tests indicates you have diabetes. A result between 5.7 and 6.4 percent is considered prediabetes, which indicates a high risk of developing diabetes.

For someone who doesn't have diabetes, a normal A1C level can range from 4.5 to 6 percent. Someone who's had uncontrolled diabetes for a long time might have an A1C level above 9 percent.

It's important to note that the effectiveness of A1C tests may be limited in certain cases. For example:

  • If you experience heavy or chronic bleeding, your hemoglobin stores may be depleted. This may make your A1C test results falsely low.
  • If you don't have enough iron in your bloodstream, your A1C test results may be falsely high.
  • Most people have only one type of hemoglobin, called hemoglobin A. If you have an uncommon form of hemoglobin (known as a hemoglobin variant), your A1C test result may be falsely high or falsely low. Hemoglobin variants are most often found in blacks and people of Mediterranean or Southeast Asian heritage. Hemoglobin variants can be confirmed with lab tests. If you're diagnosed with a hemoglobin variant, your A1C tests may need to be done at a specialized lab for the most accurate results.

Also keep in mind that the normal range for A1C results may vary somewhat among labs. If you consult a new doctor or use a different lab, it's important to consider this possible variation when interpreting your A1C test results.

William Lee Dubois
Endocrinologist

An A1C test is a quick lab test that allows your doc to get a sense of your average day and night blood sugars for the last three months.

No one quite agrees on where your A1C score should be, but we all agree on where it shouldn’t be. The scale does not look anything like the BGL numbers you are used to. For all practical purposes, it runs from 5.0 up to 14.0 where most in-house A1C machines max out. Labs can test higher, but at 14.0 your doctor will run screaming for the hills anyway, so it really doesn’t matter. At that level your blood sugar is lethal and your body is slowly dissolving, just as if you had battery acid in your veins and arteries.

Scores below 6.0 are usually considered to be in the non-diabetic range. At 9.0 we cross the threshold where kidney damage starts. The higher above 9.0 that the number is, the worse off you are because A1C tests are curvilinear.

An A1C test is run quarterly, twice a year, or once a year, depending on how good or bad your control is; how good or bad your insurance is; and your provider’s approach to diabetes care.

Even in healthy, well-controlled patients, I like to run the test every quarter. If something is starting to change I want to jump on it right away. Remember: all diabetes is chronic and progressive and the body eventually adapts to all meds; they will lose their effectiveness.

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Phil Southerland
Healthcare Specialist

A1c is a commonly used three-month average measure of your blood sugar. Instead of making it a perfunctory measurement, I recommend using that three-month window as a way to both challenge and reward yourself to reach a goal A1c measurement of 6.5. This is just a little higher than normal blood sugar, but lower than the 8 or 9 that many diabetics commonly have. While reaching 6.5 doesn’t mean your diabetes is “cured,” it’s something your doctor will applaud, and it shows that you are successfully managing your disease.

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Mr. Eliot LeBow, CDE, LCSW
Endocrinologist

HbA1C is a measurement of the amount of glycosylated hemoglobin in your blood. Glycosylated hemoglobin is created when glucose (blood sugar) attaches to the hemoglobin in red blood cells. The Higher the HbA1C you have the more glucose in your blood over a 2-3 month period of time. For optimum management of diabetes, the HbA1C test should be taken every 3 months.

The higher your HbA1c levels, the higher the risk of developing future problems such as heart disease, nerve damage, eye disease, kidney disease and stroke. If your HbA1c remains high for a long period of time this will increase the risk but the closer to normal levels the lower the risk for diabetes-related diseases.

Normal levels for people with diabetes are 7 percent and below. If your child’s HbA1c is higher then 8 percent depending on age, (set by American Diabetes Association) then treatment (insulin, quantity of blood tests, etc.), exercise or diet need changing.

A hemoglobin A1c level less than 7 percent means that the blood sugar should only go above 150 mg/dl after a snack or meal for a few hours. On average, a person without diabetes HbA1c level is between 4 to 6 percent. Blood sugars of 70 mg/dl, or lower are dangerous and should be avoided.

Most doctors I have encountered want your sugar levels to be between 70-120 mg/dl but my recommendation is a target area of 80 to 140mg/dl for adults with a goal of 100mg/dl. This blood glucose range is less stressful on the individual living with diabetes and is more obtainable. The American Diabetes Association has set age appropriate levels:

  1. For children younger then 6 years old, the target is 8.5 percent
  2. For six to 12 year olds, the target is under 8 percent
  3. For teens age 13 to 19, the target is under 7.5 percent
  4. For adults, the target is under 7 percent
Dr. Jack Merendino, MD
Endocrinologist

The hemoglobin A1c (many people just say “A1c”) is a blood test that reflects average blood sugar levels in your blood stream over the preceding two to three months. The higher your average blood sugar levels have been during this time, the higher the hemoglobin A1c levels are. People who do not have diabetes typically have hemoglobin A1c levels under 5.7. Someone with very poorly controlled blood sugar may have a value over 10.

Several major studies have shown that people with hemoglobin A1c levels close to the normal range will have fewer problems related to diabetes over time, especially where problems with the eyes, kidneys and nerves are concerned. Therefore, people are often told that they should strive to get their hemoglobin A1c under 7. That’s usually a good target, but there are exceptions. 

Everyone knows that very low blood sugars (hypoglycemia) are dangerous. The lower your average blood sugar level is, the more likely you are to have episodes of a low blood sugar. Therefore, for most people the risk of low sugar reactions is what limits how far they can lower their hemoglobin A1c. For example, several other studies have shown a higher mortality for people who have hemoglobin A1c levels that are too low. In these studies, having a value in the low- to mid-5 range appeared more dangerous than having values in the 6-range. People who are at high risk of low blood sugar reactions, or those who have less concern about long-term complications, may have targets that are higher than 7. An example might be a person who really does not feel the symptoms of a low blood sugar, or a person in his or her 80s who needs to be more concerned about short-term low sugar reactions rather than complications that will develop over many years. On the other hand, if some is being treated with diet only, or is taking only metformin, which does not cause hypoglycemia on its own, it is very safe for them to have hemoglobin A1c levels in the 5 range. 

One more very important point:  the hemoglobin A1c represents an average, but fluctuations in the blood sugar are also very important. It’s generally safer to have blood sugars that don’t vary widely. For my patients I would rather have a hemoglobin A1c that is a touch higher without too many peaks and valleys than to have a lower value with wide swings all the time. Best of both worlds: numbers that are close to normal and don’t jump around too much.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.