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Is Fasting Necessary For A1c Test

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Race And Ethnicity Can Affect A1c

What is the difference between A1c and Fasting Blood Glucose Testing?

The A1C test works best on hemoglobin A, the most common type of hemoglobin that people have. But depending on where in the world you come from, your blood might have a different type of hemoglobin. These are called hemoglobin variants, and they are more common if you or your family come from Africa, South and Southeast Asia, or the Mediterranean.;

Having a hemoglobin variant such as hemoglobin S, C, D, or E, can affect the accuracy of an A1C result. Luckily, many labs now run A1C tests that are not affected by hemoglobin variants. There is a full list here. If you have a hemoglobin variant, you and your provider can work together to find a lab that will give you accurate A1C results.;

How Is The A1c Test Used After Diagnosis Of Diabetes

Your health care professional may use the A1C test to set your treatment goals, modify therapy, and monitor your diabetes management.

Experts recommend that people with diabetes have an A1C test at least twice a year.4 Health care professionals may check your A1C more often if you arent meeting your treatment goals.4

Preparing For The A1c Test

An A1c test alone does not require you to be fasting, but your provider is likely drawing other labs at the same time and some of those may require you to be fasting. You should always check with your doctor to see if the labs they are drawing require you to be fasting or not. If so, you are better off scheduling your lab draw shortly after you wake up so that you dont have to go too long without eating, especially if you take any diabetes medications that could cause a low blood sugar reaction. Once your blood has been drawn, the results can come back as soon as an hour or as long as several days. How quickly the results come back depends on the lab and if they process it in house or if it has to be sent out. Steroids can cause high blood sugars and depending on the dosage and duration of use, they could effect your A1C result. Drinking plenty of water before a blood draw is also important.

Read Also: How Many Calories Should You Eat When Doing Intermittent Fasting

How Nuffield Health Can Help You Get A Blood Test

At Nuffield Health we offer a wide range of blood tests including ones that require fasting.

Our range of in-depth Health Assessments include a variety of common blood tests that will give you a clear picture of your overall health and fitness.

If youre looking for a specific blood test or have been referred for a test by a medical professional, you can easily book and purchase blood tests online through our pathology direct service.

Contact us about blood tests at Nuffield Health

Fill in the form below and we’ll get back to you within one working day. If it’s urgent, you can call us on 0300 123 6200.

Thank you

What Do The Results Of The Test Mean

Is Fasting Required For Hba1c Test?

The test result is usually given as a percentage. The normal A1c is less than 5.7%. You have a higher risk for diabetes if your A1c is 5.7% to 6.4%. If your level is 6.5% or higher, you have diabetes.

The A1c test result also can be used to find your estimated average glucose, or eAG. Your eAG and A1c show the same thing in two different ways. They both help you learn more about your average blood sugar range over the past 2 to 3 months. A1c is shown as a percentage, while eAG uses the same units as your glucose meter.


Read Also: Can You Drink Alcohol While Intermittent Fasting

What You Need To Know About Fasting Lab Tests

If youre not feeling well and your doctor isnt sure why, he or she may order lab tests to help better understand whats going on inside your body. One test they may order is a fasting lab test. Before this blood test, you may be asked to stop eating or drinking for a few hours before.

While not all lab tests require it, some tests require fasting for the most accurate results. Most of the time, this means youll be asked to stop having any food or liquid between eight to 24 hours before your lab test or bloodwork, depending on the test.

Can You Drink Coffee If Youre Fasting Before A Blood Test

Even if you drink it black, coffee can interfere with blood test results. Thats because it contains caffeine and soluble plant matter, which might skew your test results.

Coffee is also a diuretic, which means that it will increase how much you pee. This can have a dehydrating effect. The less hydrated you are, the harder it can be for the nurse or other medical professional whos doing your blood test to find a vein. This can make the blood test harder or more stressful for you.

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The Pros And Cons Of Diagnosing Diabetes With A1c

  • Enzo Bonora, MD, PHD and
  • Jaakko Tuomilehto, MD, MA, PHD
  • 1Division of Endocrinology and Metabolism, Department of Medicine, University and University Hospital of Verona, Verona, Italy
  • 2Department of Public Health, University of Helsinki, Helsinki, Finland; South Ostrobothnia Central Hospital, Seinajoki, Finland; and Red RECAVA Grupo RD06/0014/0015, Hospital Universitario La Paz, Madrid, Spain
  • Corresponding authors: Enzo Bonora, enzo.bonoraunivr.it, and Jaakko Tuomilehto, tuomilehmappi.helsinki.fi.

    An International Expert Committee was convened in 2008 by the American Diabetes Association , the European Association for the Study of Diabetes, and the International Diabetes Federation to consider the means for diagnosing diabetes in nonpregnant individuals, with particular focus on the possibility to indicate A1C as an alternative if not a better tool . After reviewing the available literature and a thorough discussion on the advantages and the limits of previous diagnostic strategies and the considered alternative approach , a consensus was reached that the latter should be included among diagnostic tools for diabetes and, with the exception of a number of clinical conditions, should even be preferred in diabetes diagnosis in nonpregnant adults.

    Hemoglobin A1c Not Reliable In Diagnosing Type 2 Diabetes

    Important Diabetes Test: Hemoglobin A1C

    With Maria Mercedes Chang Villacreses, MD, and Elena Christofides, MD, FACE

    The test that doctors most often rely on to detect a persons risk for prediabetes and type 2 diabetesthe hemoglobin A1c blood testtoo often delivers a poor reading, thereby missing the diagnosis in nearly three out of four at-risk individuals,1;according to research presented at the Endocrine Society meeting in New Orleans, Louisiana.

    The investigators compared the accuracy of the A1c test with the other screening method used to assess patients risk of diabetesthe oral glucose tolerance test to arrive at this startling conclusion.1

    The common use of the hemoglobin A1c test to screen for prediabetes and type 2 diabetes should be skipped in place of more reliable tests. Photo: 123rf

    “The A1c missed almost 73% of the people with diabetes in comparison to the oral glucose tolerance test,” says Maria Mercedes Chang Villacreses, MD, a clinical endocrinology fellow at the City of Hope Diabetes and Metabolism Research Institute in Duarte, California, who introduced the findings at the annual meeting of the Endocrine Society but are considered preliminary until published in a peer-reviewed medical journal.

    Since the fasting blood test requires a person to fast, the OGTT measures the body’s response to sugar; it requires a person to fast overnight. First, blood is taken, then the person drinks a sugary drink. Blood is taken again two hours later.

    Ultimate Guide To The A1c Test: Everything You Need To Know

    By Angela Manderfeld MS, RD, LD, CDE

    The A1C is a blood test that gives us an estimated average of what your blood sugar has been over the past 2-3 months. The A1c goes by several different names, such as Hemoglobin A1C, HbA1C, Hb1C, A1C, glycated hemoglobin, glycohemoglobin and estimated glucose average.

    Which Blood Tests Require Fasting

    We all have come across some situation in our lives where we are required to undergo blood test either as a part of a normal checkup or if we are unwell. You may notice, that your clinician advice you to visit the laboratory on an empty stomach. Your physician may advise you some hours of fasting before calling you in to draw blood.

    Fasting before a test means that you are not supposed to eat or even drink water for about 8-12 hours before your blood test. You are also not allowed to smoke or chew gum.

    Why do they ask you to fast? Which are the blood tests require fasting? What happens if I dont fast? and can we take any medications before fasting blood test? These are some questions clinicians always come across. This article will feed your curiosity regarding fasting for blood tests and will give you an insight into which blood tests require fasting and for how long.

    What If I Accidentally Eat Or Drink Before My Blood Test

    If you have been instructed to fast before your blood test and you accidentally eat or drink something during the fasting window, it is important to notify your healthcare provider or the person drawing your blood. If you dont, your results could be incorrectly interpreted.

    It may be possible for your healthcare provider to interpret the non-fasted test results. Most likely, they will instruct you to reschedule the blood test at a time when you will be able to successfully complete the fast before the test.

    Your physician will let you know the steps you need to take before your blood test, including whether or not fasting is required and for how long. By following all testing instructions and best practices , you can ensure a smooth testing process and the most accurate results.

    Best To Avoid Reliance On A1c In Making An Initial Diagnosis Of Diabetes

    Is A1c test fasting necessary?

    The shortcomings of the A1c test are known, says Elena Christofides, MD, FACE, an endocrinologist and CEO of Endocrinology Associates, in Columbus, Ohio, upon reviewing the study for EndocrineWeb.

    While she takes issue with some of the researchers statistical methods, such as how they grouped those with an abnormal glucose tolerance test together with those with a full-blown diabetes for the analysis, she says they are not the first to conclude that the A1c test is not a great tool to capture diabetes diagnoses accurately for most individuals.

    When the ADA guidelines were in development,3 Dr. Christofides tells EndocrineWeb, ”there were significant arguments back and forth about even permitting the continued use of the HbA1c testdue to the fact that it would indeed miss a number of individuals. That is why the use of the A1c is still being used but the OGTT is still thought to be the more definitive test.”

    “The guidelines also state that if the A1c is normal and there is still a suspicion of prediabetes or diabetes, doctors are advised to do the OGTT anyway,” she says. So an A1c can be done so long as you are then advised to have another test to check your blood sugar levels if there is any concern regarding your risks.

    A Need To Update Older Guidelines

    Aldasouqi also points out that specialists currently recognize that eating before undergoing a blood cholesterol test is unlikely to affect relevant measurements. Therefore, having a meal before going in for a test may actually be better than fasting and potentially losing consciousness on the way to the laboratory.

    He adds that the idea of fasting before a blood test comes from antiquated sets of guidelines from the 1970s, which specialists in Canada and most European countries no longer use.

    For this reason, he says that United States-based specialists may want to consider revising their own guidelines to better fit the needs of their patients.

    According to the studys findings, only 35 percent of participants had received advice about how to prevent a FEEHD event before going in for a blood cholesterol test.

    We encourage patients who receive orders for a lab test, explains Aldasouqi, to ask their doctor if fasting is really necessary, and if so, how they should handle their diabetes medications during the fasting period to account for the changes in their blood sugar levels.

    FEEHD is overlooked in clinical practice, and we aim to bring this problem to light and further educate doctors and patients about the consequences of fasting while on diabetes medications, he adds.

    Fasting Blood Glucose Level

    A glucose level below 11.1 mmol/L on a random blood sample does not rule out diabetes. A blood test taken in the morning before you eat anything is a more accurate test. Do not eat or drink anything except water for 8-10 hours before a fasting blood glucose test. A level of 7.0 mmol/L or more indicates that you have diabetes.

    If you have no symptoms of diabetes but the blood test shows a glucose level of 7.0 mmol/L or more, the blood test must be repeated to confirm you have diabetes. If you do have symptoms and the blood test shows a glucose level of 7.0 mmol/L or more, the test does not need to be repeated. See the separate leaflets called Type 1 Diabetes and Type 2 Diabetes for more details.

    Why Do Some Tests Require Fasting

    Blood tests give doctors an understanding and baseline of ones health. However, when a patient consumes foods and/or drinks before a blood test, it can interfere with a bodys typical nutrient levels. For example, if a patient is hypoglycemic, eating foods before a blood test could spike their blood sugar levels, inhibiting the physicians ability to detect abnormalities and correctly diagnose their condition. It is difficult for the physician to distinguish whether it is a behavior that influences the results or if they are genuinely at a normal range .

    What Is A1c Compared To Eag

    Understanding Blood Test Video 1: Lipid Profile and Hemoglobin A1C

    If you have diabetes and track glucose with a home monitor, your healthcare provider might report A1C results as eAG. This converts the information to a different way of measuring. You can then compare it to the results of home glucose monitoring.

    Instead of a percentage, eAG gets reported in milligrams per deciliter or millimoles per liter . For example, an A1c level of 7% equals an eAG of 154 mg/dl and 8.6 mmol/l. The American Diabetes Association offers a calculator and chart to help you convert your numbers.

    How To Choose A Kit

    Several FDA-approved home A1C test kits are available at pharmacies and online retailers. Some health insurance plans cover the cost, which can run between $50 to $150.

    Accessories for the test, such as replacement strips, are sold as well, so be sure to check that you have all of the necessary parts. A very inexpensive box might contain only a few replacement accessories.

    Buy your device from a reputable brand, and make sure the packaging is sealed before first use.

    Currently approved brands include:

    • Testing instructions from the manufacturer

    How The A1c Test Works

    The A1C test has been used since the late 1970s as a measure of how well diabetes is managed, but the ADA had not previously recommended it for diagnosing the disease.

    In part, this is because earlier versions of the test were not as accurate as current versions.

    The test measures the percentage of glycated hemoglobin, or A1C, in the blood and provides an assessment of blood sugar levels over the previous two to three months.

    Hemoglobin is a protein on red blood cells that carries oxygen in the blood. When blood sugar is too high it combines with hemoglobin.

    The more excess glucose in the blood, the higher the percentage of A1C. Healthy adults without diabetes or prediabetes have an A1C of about 5%. Diabetes patients with very poorly controlled disease can have levels as high as 25%.

    Under the new recommendations, people with A1C levels between 5.7% and 6.4% will be considered to have prediabetes and those with levels of 6.5% or higher will be considered to have diabetes.

    Diabetes testing is recommended for:

    • Any adult who is overweight or obese with one or more additional risk factor for diabetes including: having a family history of the disease, belonging to a high-risk ethnic group , having high blood pressure or a history of gestational diabetes.
    • Anyone who is age 45 or older, regardless of risk factors.

    What Is A Good A1c Level

    Levels between 5.7 and 6.4 are considered prediabetes. For most people with diabetes, the general A1C goal is to have a level between 6.0 and 6.9. While it might sound like the ideal A1C target is under 6.0, for those with diabetes, this level can indicate low blood sugar levels, which can be just as dangerous as high blood sugar levels. If A1C results fall between 7.0 and 8.9, a doctor might suggest lifestyle changes or medications to help lower the levels to what is considered controlled. However, for some people, these levels might be appropriate, such as:

    • Those with a limited life expectancy
    • People with long-standing diabetes who have trouble reaching a lower goal
    • Those with severe hypoglycemia or the inability to sense hypoglycemia;

    What If My Hba1c Is Normal But My Glucose Is Above Optimized

    What is the A1C Test for Diabetes? (with pictures)

    Sleep deprivationTheres evidence that poor sleep patterns impair glucose metabolism. People on restricted sleep demonstrate worsened insulin response to food, resulting in higher blood glucose spikes. In one study, sleep-deprived people had higher glucose and insulin levels after consuming breakfast compared to those who slept a healthy eight hours. Other studies confirm this findinginsulin resistance is more common in people deprived of sleep.;

    StressThe body releases a steroid hormone called cortisol to activate our “flight-or-fight” responses to counteract acutely stressful situations. Cortisol stimulates the release of blood glucose by breaking down its storage form, glycogen. If youve experienced a stressful week, good chances are your blood sugars may be slightly higher than normal.;

    FoodBecause glucose fluctuates after meals, we recommend fasting for a full 12 hours prior to getting a blood test for an accurate reading. This means water only, not even black coffee. People react differently to coffee so we suggest to err on the side of caution and stick to just water.

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