What is the A1C check?
The A1C check is a blood check that provides details about a person’s average ranges of blood glucose, additionally referred to as blood sugar, over the previous three months. The A1C check is usually referred to as the hemoglobin A1c, HbA1c, or glycohemoglobin check. The A1C check is the primary check used for diabetes administration and diabetes analysis.
How does the A1C check work?
The A1C check is predicated on the attachment of glucose to hemoglobin, the protein in pink blood cells that carries oxygen. Within the body, pink blood cells are continuously forming and dying, however sometimes they reside for about 3 months. Thus, the A1C check reflects the typical of an individual’s blood glucose levels over the past three months. The A1C check result is reported as a proportion. The larger the share, the upper a person’s blood glucose levels have been. A traditional A1C degree is under 5.7 %.
Can the A1C check be used to diagnose sort 2 diabetes and prediabetes?
Yes. In 2009, a world skilled committee really helpful the A1C check as one of many exams out there to help diagnose sort 2 diabetes and prediabetes. 1 Previously, only the normal blood glucose exams have been used to diagnose diabetes and prediabetes.
Because the A1C check does not require fasting and blood could be drawn for the check at any time of day, specialists are hoping its comfort will permit more individuals to get examined—thus, reducing the variety of individuals with undiagnosed diabetes. Nevertheless, some medical organizations continue to advocate using blood glucose exams for analysis.
1 The Worldwide Skilled Committee. International Professional Committee report on the position of the A1C assay within the analysis of diabetes. Diabetes Care. 2009;32(7):1327–1334.
Why should an individual be examined for diabetes?
Testing is particularly necessary because early within the illness diabetes has no symptoms. Though no check is perfect, the A1C and blood glucose checks are the most effective instruments obtainable to diagnose diabetes—a critical and lifelong disease.
Testing allows well being care providers to seek out and treat diabetes earlier than problems occur and to seek out and treat prediabetes, which may delay or forestall sort 2 diabetes from creating.
Has the A1C check improved?
Sure. A1C laboratory checks at the moment are standardized. Prior to now, the A1C check was not really helpful for analysis of sort 2 diabetes and prediabetes because the various several types of A1C exams might give diversified outcomes. The accuracy has been improved by the National Glycohemoglobin Standardization Program (NGSP), which developed requirements for the A1C checks.
The NGSP certifies that manufacturers of A1C exams present checks which are in line with these used in a serious diabetes research. The research established current A1C objectives for blood glucose control that can scale back the prevalence of diabetes problems, similar to blindness and blood vessel illness. 2
2 Nathan DM, Genuth S, Lachin J, et al. The effect of intensive remedy of diabetes on the development and development of long-term problems in insulin-dependent diabetes mellitus. The New England Journal of Drugs. 1993:329(14)977–986.
How is the A1C check used to diagnose sort 2 diabetes and prediabetes?
The A1C check can be utilized to diagnose sort 2 diabetes and prediabetes alone or in combination with other diabetes checks. When the A1C check is used for analysis, the blood sample have to be despatched to a laboratory that uses an NGSP-certified technique for analysis to make sure the results are standardized.
Blood samples analyzed in a health care provider’s office, generally known as point-of-care (POC) exams, aren’t standardized for diagnosing diabetes. The following table supplies the odds that point out diagnoses of regular, diabetes, and prediabetes based on A1C levels.
* Any check for analysis of diabetes requires confirmation with a second measurement until there are clear symptoms of diabetes.
Having prediabetes is a danger factor for getting sort 2 diabetes. Individuals with prediabetes may be retested annually. Inside the prediabetes A1C range of 5.7 to 6.Four %, the higher the A1C, the larger the danger of diabetes. These with prediabetes are more likely to develop sort 2 diabetes inside 10 years, however they will take steps to stop or delay diabetes.
Is the A1C check used throughout pregnancy?
The A1C check could also be used on the first visit to the well being care provider during pregnancy to see if ladies with danger elements had undiagnosed diabetes earlier than turning into pregnant. After that, the oral glucose tolerance check (OGTT) is used to test for diabetes that develops throughout being pregnant—often known as gestational diabetes. After supply, ladies who had gestational diabetes must be tested for persistent diabetes. Blood glucose exams, quite than the A1C check, ought to be used for testing within 12 weeks of delivery.
Can blood glucose checks still be used for diagnosing sort 2 diabetes and prediabetes?
Sure. The commonplace blood glucose checks used for diagnosing sort 2 diabetes and prediabetes-the fasting plasma glucose (FPG) check and the OGTT—are nonetheless really helpful. The random plasma glucose check, also referred to as the casual glucose check, could also be used for diagnosing diabetes when signs of diabetes are current. In some instances, the A1C check is used to help well being care providers affirm the results of a blood glucose check.
Can the A1C check end in a unique analysis than the blood glucose exams?
Sure. In some individuals, a blood glucose check might indicate a analysis of diabetes while an A1C check doesn’t. The reverse may also occur—an A1C check might indicate a analysis of diabetes regardless that a blood glucose check does not. Due to these variations in check outcomes, health care providers repeat checks earlier than making a analysis.
Individuals with differing check results may be in an early stage of the disease, the place blood glucose ranges have not risen high sufficient to point out on each check. Typically, making simple modifications in way of life—dropping a small amount of weight and growing bodily exercise—might help individuals in this early stage reverse diabetes or delay its onset.
Are diabetes blood check results all the time accurate?
All laboratory check results can differ from daily and from check to test. Outcomes can range
- inside the individual being examined. An individual’s blood glucose levels usually move up and down depending on meals, train, illness, and stress.
- between totally different exams. Every check measures blood glucose levels differently. For example, the FPG check measures glucose that is floating free in the blood after fasting and solely exhibits the blood glucose degree on the time of the check. Repeated blood glucose exams, comparable to self-monitoring a number of occasions a day with a home meter, can report the pure variations of blood glucose levels in the course of the day. The A1C check represents the quantity of glucose hooked up to hemoglobin, so it displays a mean of all of the blood glucose ranges a person might expertise over 3 months. The A1C check won’t present day-to-day modifications.
The following chart exhibits how multiple blood glucose measurements over 4 days examine with an A1C measurement.
Blood Glucose Measurements In contrast with A1C Measurements Over 4 Days
Observe: Blood glucose (mg/dL) measurements have been taken four occasions per day (fasting or pre-breakfast, pre-lunch, pre-dinner, and bedtime).
The straight black line indicates an A1C measurement of 7.zero %. The blue line exhibits blood glucose check outcomes from self-monitoring four occasions a day over a 4-day period.
- inside the similar check. Even when the identical blood sample is repeatedly measured in the same laboratory, the results might range because of small modifications in temperature, gear, or pattern dealing with.
Well being care suppliers take these variations under consideration when considering check outcomes and repeat laboratory checks for affirmation. Diabetes develops over time, so even with variations in check results, well being care suppliers can tell when general blood glucose levels have gotten too excessive.
Evaluating check results from totally different laboratories may be misleading. Individuals should contemplate requesting new laboratory exams once they change well being care suppliers, or if their well being care provider’s workplace modifications the laboratory or clinic it uses for blood testing.
How correct is the A1C check?
The A1C check end result could be up to 0.5 % greater or lower than the precise proportion. This means an A1C measured as 7.0 % might point out a real A1C anyplace within the vary from ~6.5 to 7.5 %.
The drawing under illustrates the vary of potential true values when an A1C is 7.zero % on the lab report. This vary is predicated on the inherent variability of the laboratory check, also known as the coefficient of variation. Totally different levels of laboratory variability end in totally different ranges of potential true values. The vary illustrated is the maximum allowed by check strategies permitted by NGSP.
Courtesy of David Aron, M.D., Louis Stokes Department of Veterans Affairs Medical Middle
To place the A1C check into perspective, an FPG check result of 126 mg/dL obtained from a laboratory check accounting for typical variability within a person individual might indicate a real FPG anyplace in the vary from ~110 to 142 mg/dL. This variation shall be even higher if the blood sample is just not processed promptly or just isn’t placed on ice, inflicting blood glucose ranges within the sample to lower. The drawing under illustrates the vary of potential true values for an FPG of 126 mg/dL.
Courtesy of David Aron, M.D., Louis Stokes Division of Veterans Affairs Medical Middle
Can the A1C check give false outcomes?
Sure, for some individuals. The A1C check might be unreliable for diagnosing or monitoring diabetes in individuals with sure circumstances which might be recognized to intrude with the outcomes. Interference ought to be suspected when A1C outcomes appear very totally different from the results of a blood glucose check.
Individuals of African, Mediterranean, or Southeast Asian descent, or individuals with relations with sickle cell anemia or a thalassemia are notably vulnerable to interference. Individuals in these groups might have a less widespread sort of hemoglobin, referred to as a hemoglobin variant, that can intrude with some A1C checks. Most individuals with a hemoglobin variant haven’t any symptoms and should not know that they carry one of these hemoglobin.
Not all the A1C exams are unreliable for individuals with a hemoglobin variant. Individuals with false outcomes from one sort of A1C check may have a special sort of A1C check for measuring their average blood glucose degree. The NGSP offers info for health care providers about which A1C exams are applicable to use for specific hemoglobin variants at www.ngsp.org .
More information about problems with the A1C check and totally different types of sickle cell anemia is offered within the NIDDK well being subjects:
False A1C results can also happen in individuals with different problems that have an effect on their blood or hemoglobin. For instance, a falsely low A1C outcome can happen in individuals with
A falsely elevated A1C outcome can occur in people who
- are very low in iron, for example, those with iron deficiency anemia
Different causes of false A1C outcomes embrace
- kidney failure
- liver disease
How is the A1C check used after analysis of diabetes?
Well being care providers can use the A1C check to watch blood glucose levels in individuals with sort 1 or sort 2 diabetes. The A1C check just isn’t used to watch gestational diabetes.
The American Diabetes Affiliation recommends that folks with diabetes who’re meeting remedy objectives and have secure blood glucose levels have the A1C check twice a yr. Well being care providers might repeat the A1C check as typically as 4 occasions a yr till blood glucose ranges reach advisable ranges.
The A1C check helps health care suppliers regulate treatment to scale back the danger of long-term diabetes problems. Studies have demonstrated substantial reductions in long-term problems with the decreasing of A1C levels.
When the A1C check is used for monitoring blood glucose ranges in a person with diabetes, the blood pattern may be analyzed in a health care supplier’s workplace utilizing a POC check to offer quick results. Nevertheless, POC checks are less reliable and not as accurate as most laboratory checks.
How does the A1C relate to estimated average glucose?
Estimated average glucose (eAG) is calculated from the A1C. Some laboratories report eAG with the A1C check outcomes. The eAG quantity helps individuals with diabetes relate their A1C to every day glucose monitoring levels. The eAG calculation converts the A1C proportion to the same models used by house glucose meters—milligrams per deciliter (mg/dL).
The eAG number won’t match every day glucose readings as a result of it’s a long-term common somewhat than the blood glucose degree at a single time, as measured with the house glucose meter. The following table exhibits the connection between the A1C and the eAG.
Relationship between A1C and eAG
What A1C goal ought to individuals have?
Individuals may have totally different A1C targets relying on their diabetes history and their basic health. Individuals ought to talk about their A1C goal with their health care supplier. Studies have shown that folks with diabetes can scale back the danger of diabetes problems by protecting A1C ranges under 7 %.
Sustaining good blood glucose control will profit these with new-onset diabetes for a few years to return. Nevertheless, an A1C degree that’s protected for one individual is probably not protected for an additional. For instance, preserving an A1C degree under 7 % will not be protected if it results in problems with hypoglycemia, also referred to as low blood glucose.
Much less strict blood glucose management, or an A1C between 7 and 8 %—or even larger in some circumstances—may be applicable in people who have
- limited life-expectancy
- long-standing diabetes and problem attaining a lower aim
- extreme hypoglycemia
- superior diabetes problems akin to persistent kidney illness, nerve problems, or cardiovascular disease
Will the A1C check show modifications in blood glucose levels?
Giant modifications in a person’s blood glucose levels over the past month will present up of their A1C check end result, but the A1C doesn’t present sudden, momentary will increase or decreases in blood glucose levels. Regardless that the A1C represents a long-term average, blood glucose levels inside the previous 30 days have a higher effect on the A1C reading than those in previous months.
Points to Keep in mind
- The A1C check is a blood check that provides information about a person’s average levels of blood glucose, also referred to as blood sugar, over the previous 3 months.
- The A1C check is predicated on the attachment of glucose to hemoglobin, the protein in pink blood cells that carries oxygen. Thus, the A1C check reflects the typical of a person’s blood glucose ranges over the previous three months.
- In 2009, a world professional committee advisable the A1C check be used as one of the checks obtainable to assist diagnose sort 2 diabetes and prediabetes.
- As a result of the A1C check doesn’t require fasting and blood could be drawn for the check at any time of day, specialists are hoping its convenience will permit more individuals to get examined—thus, reducing the variety of individuals with undiagnosed diabetes.
- Prior to now, the A1C check was not beneficial for analysis of sort 2 diabetes and prediabetes as a result of the various several types of A1C checks might give assorted results. The accuracy has been improved by the Nationwide Glycohemoglobin Standardization Program (NGSP), which developed requirements for the A1C checks. Blood samples analyzed in a health care provider’s office, referred to as point-of-care (POC) exams, aren’t standardized to be used in diagnosing diabetes.
- The A1C check could also be used on the first visit to the health care supplier during pregnancy to see if ladies with danger elements had undiagnosed diabetes earlier than turning into pregnant. After that, the oral glucose tolerance check (OGTT) is used to check for diabetes that develops throughout pregnancy—referred to as gestational diabetes.
- The normal blood glucose checks used for diagnosing sort 2 diabetes and prediabetes—the fasting plasma glucose (FPG) check and the OGTT—are nonetheless beneficial. The random plasma glucose check could also be used for diagnosing diabetes when signs of diabetes are current.
- The A1C check might be unreliable for diagnosing or monitoring diabetes in individuals with sure circumstances which might be recognized to intrude with the outcomes.
- The American Diabetes Association recommends that folks with diabetes who’re assembly remedy objectives and have secure blood glucose ranges have the A1C check twice a yr.
- Estimated average glucose (eAG) is calculated from the A1C to assist individuals with diabetes relate their A1C to day by day glucose monitoring levels.
- Individuals could have totally different A1C targets relying on their diabetes historical past and their common well being. Individuals ought to talk about their A1C target with their health care supplier.