The A1C test, also known as HbA1C, hemoglobin A1C, glycosylated hemoglobin, or glycosylated hemoglobin test , is a blood test used to diagnose and monitor diabetes. Shows your average blood sugar level for the past two to three months. It is a more comprehensive test than regular home glucose monitoring , which measures your blood sugar at any time.
The purpose of the test
Hemoglobin A, a protein found in red blood cells, carries oxygen throughout the body. When there is glucose in the bloodstream, it can adhere (glycate) to hemoglobin A. The more glucose in the blood, the more it does, creating a higher percentage of glycosylated hemoglobin proteins.
Lack of insulin or insulin resistance results in higher than normal blood glucose levels.
Once glucose attaches to the hemoglobin protein, it generally remains there for the life of the hemoglobin A protein (up to 120 days). This means that, at any given time, the glucose bound to the protein hemoglobin A reflects the level of sugar in the blood during the last two to three months.
The A1C test measures how much glucose is actually trapped in hemoglobin A, or more specifically, what percentage of the proteins in hemoglobin are glycosylated. Hemoglobin with glucose attached to it is called A1C. Therefore, having 7% A1C means that 7% of hemoglobin proteins are glycosylated.
Depending on why your healthcare provider orders the test, a blood sample may be obtained through a routine blood draw or by pricking a finger with a lancet.
Your healthcare provider may request an A1C test for the following reasons.
If you are overweight or obese and have one or more risk factors for developing type 2 diabetes , your healthcare provider will most likely order an A1C test as part of your annual physical exam.
These risk factors include:
Most people who end up with type 2 diabetes have prediabetes first, which means that their blood sugar levels are above normal but not high enough to be diagnosed with diabetes. An A1C test can help track this condition.
The American Diabetes Association (ADA) also recommends taking the A1C test for everyone age 45 and older, regardless of other risk factors, as age itself is a major risk factor. If your test results are normal, you should take an A1C at least every three years.
If you have been diagnosed with gestational diabetes (diabetes during pregnancy) that resolves after the baby is born, you will need to be tested at least every three years for the rest of your life.
The A1C test can also be used to screen high-risk pregnant women for undiagnosed pre-existing diabetes , but only in the first trimester. In the second and third trimesters, diabetes should be controlled with a glucose challenge test (also known as an oral glucose tolerance test).
Diagnosis of diabetes
If you have symptoms such as the need to urinate more often, excessive thirst and drinking more than usual, increased appetite, fatigue, cuts or bruises that heal slowly, and / or blurred vision, your healthcare provider may order an A1C test. to verify. have diabetes. Other symptoms may include weight loss or pain, tingling, or numbness in the arms or legs.
Your healthcare provider may order a random plasma glucose test at the same time if you have these symptoms. This test measures your blood sugar level while you take blood.
If symptoms appear suddenly and your healthcare provider suspects that you have acute-onset type 1 diabetes , you may be scheduled for a plasma glucose test instead of an A1C for diagnosis. However, some healthcare providers may also do an A1C test to find out how long your blood sugar has been high.
If you have been diagnosed with type 1 or type 2 diabetes, you will have regular A1C tests or other glycemic tests to keep track of how well your condition is being controlled and how effective your treatment is.
The frequency of testing will depend on the type of diabetes you have, how well it is controlled, and what your healthcare provider recommends, but it will most likely be at least twice a year.
There are conditions in which the A1C test is not a reliable source for diagnosing diabetes, including:
These conditions can produce distorted results that do not reflect actual blood sugar levels. If you have one of these conditions, a fasting plasma glucose test and an oral glucose tolerance test may be used instead for diagnosis.
Additionally, the A1C test should be performed using standardized, NGSP -certified methods so that the Diabetes and Complications Control Study (DCCT) analysis is as accurate as possible.
Before the test
Once your healthcare provider recommends an A1C test, they will tell you if they are going to do a random plasma glucose test at the same time. If you have questions about what your healthcare provider is looking for or what to expect, it's time to ask.
The blood test generally takes less than five minutes after the technician is ready to draw your blood.
You can get this blood test directly from your PCP's office, local hospital, or laboratory.
What to wear
If the technician draws blood from a vein in the arm, it is helpful to wear short sleeves. Instead, you can also just roll up or roll up the long sleeve.
Food and drink
There are no fasting requirements for this test. The same is true for the randomized plasma glucose test.
Cost and health insurance
The A1C test is fairly inexpensive. If you have health insurance, it must be covered by insurance, as well as other lab tests, whether they are done to identify, diagnose, or manage diabetes. You may have to pay a copayment or coinsurance. Contact your insurance company if you have any questions or concerns.
You can bring something to pass the time if you have to wait a bit while the blood is donated. Have your insurance and identification ready.
You may have heard of A1C tests that you can do at home . While they may be helpful in treating your condition after you've been diagnosed with diabetes, they are not recommended for screening or diagnosing diabetes. If you have questions, talk to your doctor about it.
During the exam
A laboratory technician, often a nurse or a phlebotomist (someone specially trained to collect blood), will take your blood sample for testing.
You may need to fill out a form or two prior to the test, for example to consent to the test or to authorize your insurance billing. The administrator or nurse will let you know about this.
Be sure to inform the technician if you have a history of fainting or fainting during medical procedures. This allows the technician to take precautions, such as asking you to lie on a table while conducting a test.
Throughout the test
If your healthcare provider is evaluating or trying to rule out or diagnose diabetes, your blood will be drawn from a vein in your arm and sent to a laboratory that uses a method certified by NGSP.
The test will run as follows:
- The technician will ask you which hand you want to use (most people choose their non-dominant hand). If possible, roll up your sleeves to expose the blood collection area.
- The technician will look for a vein, usually on the inside of the arm, at the bend of the elbow, and will tie an elastic band around the arm over the vein to help push the blood down.
- After the area has been cleaned with rubbing alcohol, a small, thin needle will be inserted into the vein. You will likely feel a sharp prick, pinch, or stab that will only last for a few moments. Let the technician know if you feel weak, dizzy, or dizzy.
- Your blood will be collected in a test tube. When it begins to fill, the technician will untie the elastic band and then remove the needle from your hand.
- If the area is bleeding, apply pressure with a cotton ball or tissue for a few seconds. If this does not stop the bleeding, the technician will bandage the area.
If you have an A1C test to monitor your diabetes after you've been diagnosed, your finger will likely be pricked instead of a blood test.
Results will be determined directly in your healthcare provider's office or laboratory. This is called a point-of-care test. It's a quick process that's mildly inconvenient, but generally painless, and you'll likely get used to checking your blood sugar at home.
If you do not feel nauseous or weak, you can leave immediately after taking a blood sample. If you are not feeling well, you may need to wait a few minutes at first to recover. Once you have done this, you can go.
After the test
After completing the test, you can go home and return to your normal activities.
Management of side effects
You may have bruising, pain, or bleeding at the sample site, but it should be moderate and last only a few days. If it lasts longer or worsens, call your doctor.
interpretation of results
Depending on whether your test was done in your PCP's office or sent to a lab, your results may be available the same day, a few days later, or up to a week later.
For the detection and diagnosis of diabetes.
Reference ranges for A1C results:
- Without diabetes: below 5.7%
- Borderline / prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% and more
To monitor diabetes control
Experts disagree a bit about what the A1C goal should be. The ADA recommends an overall A1C goal of less than 7% without significant hypoglycemia (low blood sugar) , while the American Association of Clinical Endocrinologists (AACE) recommends an overall goal of 6.5% or less.
The ADA Diabetes Care Standards for 2021 include the following A1C targets:
|A1C Goals for Diabetes Control|
|Most nonpregnant adults without significant hypoglycemia||<7%|
|Adults not taking any medications or taking only oral medications; have a long shelf life; or do not have severe cardiovascular disease||The target value can be below <7%|
|Adults with limited life expectancy or advanced microvascular or macrovascular disease||<8%|
The ADA recommends setting an A1C goal below 7% only if it can be achieved without significant hypoglycemia or other side effects.
While these goals are helpful, they are general guidelines. Both the ADA and AACE emphasize that A1C goals should be customized based on factors such as:
- Other medical conditions
- How long have you had diabetes?
- How well are you following your treatment plan?
- Your risk of developing complications from hypoglycemia
For example, if it has a shorter shelf life; have long-term diabetes and trouble reaching your lower A1C goal; have severe hypoglycemia; or you have serious complications from diabetes, such as chronic kidney disease, nervous disorders, or cardiovascular disease, your A1C goal may be above 7%, but generally not above 8%.
However, for most people, lower A1C levels are ideal if they do not have frequent episodes of low blood sugar. Some people can significantly reduce the risk of diabetes complications if they can keep their A1C levels below 7%.
In general, the higher the A1C level, the greater the risk of developing complications from diabetes. Be open and honest with your doctor about the factors that can affect your A1C. They will determine what is the best goal for you.
Estimated average glucose
Some labs report mean glucose levels (eAG). This is your two to three month average glucose level expressed in mg / dL (milligrams per deciliter).
This is not the same as your A1C result, although this number is used to calculate eAG:
28.7 X A1C – 46.7 = eAG
Your A1c percentage can be converted to an estimated average blood sugar and vice versa.
For example, a mean blood glucose level of 150 mg / dL corresponds to approximately 7% A1C. This is above normal considering that diabetes is usually diagnosed when blood sugar reaches around 126 mg / dL.
The EAG is designed to help you link your A1C to home glucose monitoring, although it will not be the same as your daily level as it reflects the average over several months.
|A1C to eAg conversion table|
|HbA1c or A1C (%)||eAg (mg / dl)||eAg (mmol / l)|
Most people have one type of hemoglobin: hemoglobin A.
However, some people in Africa, the Mediterranean, South or Central America, the Caribbean, or Southeast Asia, or people who have relatives with sickle cell anemia or sickle cell anemia have hemoglobin A and the so-called hemoglobin variant. , a different kind. hemoglobin.
Having a hemoglobin variant can interfere with your A1C test, making your blood sugar appear higher or lower than it actually is.
Sometimes this variation in hemoglobin becomes apparent when your blood glucose test or home glucose monitoring tests do not match your A1C results, when your A1C result is extremely high, or if your A1C test Recent is very different from the previous one.
If your healthcare provider suspects that you have a hemoglobin variant based on your A1C results, they will likely order a blood test to confirm it. You can also request to perform this test if you are concerned.
What happens next depends on the reason you took the A1C test and your results.
Talk to your doctor about any questions or concerns you have about your A1C test result and what your next steps are.
High A1C, no symptoms of high blood sugar
If your A1C was high but you don't really have symptoms of high blood sugar, you may have had another A1C test.
Alternatively, your healthcare provider may decide to do a fasting plasma glucose (FPG) test or a two-hour glucose tolerance test right away.
To confirm a diagnosis of diabetes without obvious symptoms of high blood sugar, the results of two tests must be abnormal. It can be two results from the same test (A1C, FPG, or 2-hour tolerance test), or a result from one and a result from the other.
High A1C with symptoms of high blood sugar
If you have symptoms of high blood sugar and your baseline A1C is high, this will confirm the diagnosis of diabetes, especially if you also had a random plasma glucose test and it was high.
This means that your healthcare provider will need to see you as soon as possible to discuss starting a treatment plan to control your diabetes.
This plan will depend on whether you have type 1 or type 2 diabetes, but may include insulin supplements, medications, glucose control, exercise, and lifestyle changes.
Your healthcare provider will likely repeat the A1C shortly after starting your treatment to see how it works and how well you follow the rules.
Borderline / prediabetes
If your A1C, FPG, or 2-hour tolerance test results are at the borderline, your healthcare provider will repeat them at least every six months, as recommended by the ADA, to monitor your condition.
They will most likely also tell you about lifestyle changes you can make to prevent diabetes.
If your healthcare provider has tested you for diabetes because you have risk factors and your A1C level is normal, you will need this test at least every three years.
This may happen more often, based on initial results and other risk factors. Your healthcare provider will explain how often this test should be done.
In cases where you are taking an A1C test to control diabetes and your result is within the target range, you may only need to repeat the test twice a year.
If it's higher than your goal, your treatment plan may require some adjustments and your healthcare provider will likely repeat the test sooner.
The ADA recommends checking glycemic status with the A1C test or other glycemic tests at least twice a year for people with diabetes under control. But it can be done quarterly if you are diagnosed for the first time, your treatment plan changes, or if your diabetes is not well controlled.
If the hemoglobin variant is confirmed, A1C tests can still be done to monitor diabetes in the future, but they will need to be sent to a laboratory that uses a test that does not show the effect of such variants.
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