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Is Fasting Needed For A1c Test

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Why It Is Done

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

Blood glucose tests are done to:

  • Check for prediabetes and diabetes.
  • Monitor treatment of diabetes.
  • Check for diabetes that occurs during pregnancy .
  • Determine if an abnormally low blood sugar level is present. A test to measure blood levels of insulin and a protein called C-peptide may be done along with a blood glucose test to determine the cause of hypoglycemia.

Cost Of The Assay: Savings Or No Savings

One of the major concerns raised by critics of the use of A1C for diagnosing diabetes is the higher cost of the assay when compared with FPG. There is no doubt that from an analytical point of view , FPG is cheaper than A1C. However, other considerations about cost should be made. FPG assessment requires overnight fasting, whereas A1C can be assessed any time. This means that a person could go or could be driven by a relative/friend to the laboratory, even during lunch or in the late afternoon, avoiding loss of work hours. It is also possible to collect blood for A1C assessment in the evening and hand it to the laboratory in the following days. Yet, in subjects with FPG 7 mmol/L , A1C assessment would be needed the next few days as a second step in a newly diagnosed diabetes workup. On the contrary, when A1C assessment yields a value 6.5%, the second step required to initiate diabetes monitoring after diagnosis would be completed, with a substantial savings of both analytical and nonanalytical costs. On the other hand, when using FPG to screen for diabetes and finding a value in the range of 5.66.9 mmol/L , an OGTT is frequently prescribed to establish glucose tolerance. This test requires hours in the laboratory, with additional analytical and nonanalytical costs. In such cases, which represent a sizable portion of the general population, A1C rather than FPG would provide an immediate diabetes diagnosis or a valuable risk stratification without supplementary testing.

What Do I Do With This Information

Your A1C test can give you a good idea about your overall glucose level.

If you dont have diabetes, an A1C within target is a good sign, and you should continue making healthy lifestyle choices. If you have diabetes and your A1C is within target, thats great! Keep up your healthy choices and continue on your diabetes treatment plan.

If your A1C is on the higher side, talk to your doctor or Shoppers Drug Mart pharmacist to come up with a specialized management plan. This may involve adjusting your lifestyle habits or medications. It may also be a good idea to start self-testing your blood glucose levels at home if you havent already. You can buy a home blood glucose monitor at your local Shoppers Drug Mart store. Together, frequent blood glucose testing and knowing your current A1C value can give you greater control in managing your diabetes.1

Recommended Reading: Do’s And Don Ts Of Intermittent Fasting

What Abnormal Results Mean

An abnormal result means that you have had a high blood sugar level over a period of weeks to months.

If your A1C is above 6.5% and you do not already have diabetes, you may be diagnosed with diabetes.

If your level is above 7% and you have diabetes, it often means that your blood sugar is not well controlled. You and your provider should determine your target A1C.

The higher your A1C, the higher the risk that you will develop problems such as:

  • Eye disease

Is It Ok To Drink Water Before A Blood Test

Benefits of A1c Testing In Children

Its fine to drink water before a blood test, unless youre instructed otherwise by your doctor. This is different from some surgical procedures, which may require you to have a totally empty stomach.

Tap or bottled water are both OK, but leave the squeeze of lemon for another time. Seltzer and club soda are off-limits. Carbonated beverages, flavored or otherwise, shouldnt be consumed during a fast, and neither should any type of tea.

Also Check: What To Drink While Fasting

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.

The More Accurate Way To Do It

So now Id like to discuss a more accurate way to do all of this.

Ive always stated that the human body is very complicated. Its wrong to think that ONE drug or ONE type of diet or piece of food or ONE type of exercise or ONE vitamin or ONE specific blood or medical test, will somehow magically fix or predict a health problem.

With my clients, I test multiple factors when it comes to determining your TRUE blood sugar health.

I test for:

  • Fructosamine
  • Post-Meal Blood Sugar
  • The post-meal is the most accurate in my opinion but also takes more time and effort.

    I then look at the averages, the big picture of these 4 tests.

    If only one of them is high, then Im not too concerned.

    However, if 3 or 4 of them all show high levels, then we have a clear indicator that your body is not processing sugar correctly at the cellular level, pancreas health, and also insulin sensitivity.

    Now you need to take action by making some important lifestyle changes and improvements.

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    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.

    Can I Drink Coffee / Alcohol / Juice / Soda / Tea While Fasting

    Is the A1C Test Accurate?

    No. Any beverage other than water should not be consumed before a blood test, unless approved by your healthcare provider. Alcohol, soda, and juice contain high quantities of sugar, which can interfere with many common test results.;

    Black coffee, tea, and other caffeinated beverages are diuretics, which can have a dehydrating effect and cause test results to be inaccurate. For best results, avoid drinking all non-water beverages for the recommended amount of time before your test.

    Also Check: What Is The Best Intermittent Fasting Time

    Biological Variability Of A1c Is Lower Than That For Fpg

    When the same subjects have two assessments of the available glucose-related parameters, the correlation is stronger among the individual A1C measurements than among the FPG or 2-h PG measurements. The coefficients of variation of A1C, FPG, and 2-h PG are 3.6, 5.7, and 16.6%, respectively . This reflects of course both biological and analytical variability. However, although the latter was similar for A1C and FPG , biological variability of A1C was severalfold lower than that of FPG . This finding confirms that the two required assessments of FPG to diagnose diabetes can provide quite unreliable information, whereas A1C, especially if measured twice as recommended, provides more robust clinical information.

    Can The A1c Test Result In A Different Diagnosis Than The Blood Glucose Tests

    Yes. In some people, a blood glucose test may show diabetes when an A1C test does not. The reverse can also occuran A1C test may indicate diabetes even though a blood glucose test does not. Because of these differences in test results, health care professionals repeat tests before making a diagnosis.

    People with differing test results may be in an early stage of the disease, when blood glucose levels have not risen high enough to show up on every test. In this case, health care professionals may choose to follow the person closely and repeat the test in several months.

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    Individual Susceptibility To Glycation Might Be An Additional Benefit Of A1c Assessment

    It is a common clinical finding that many subjects have an A1C value lower or higher than expected when examining their daily glycemic profiles. Using the DCCT database, McCarter et al. calculated the hemoglobin glycation index as the difference between observed and predicted A1C level and identified categories of patients with low, moderate, or high HGI. Most interestingly, they found that subjects with high HGI had a greater risk of developing retinopathy and nephropathy, even when they had good glucose control, and that subjects with lower HGI had a low incidence of microangiopathy despite high mean blood glucose levels. This finding demonstrates that A1C assessment might provide not only information on chronic hyperglycemia but also a measure of whole-body susceptibility of protein glycation and, therefore, risks of diabetes complications that are more strictly related to this pathogenic mechanism.

    How Long Should I Fast Before Blood Test

    Over The Counter A1c Test

    You are required to fast for up to 12 hours before going for a blood test. Drinking coffee, tea or even water can affect blood test results.

    Avoid Over Fasting, this particularly applies to diabetic individuals and pregnant women. Over fasting can cause dehydration and hypoglycemia in diabetics. Over fasting can also sometimes alter test results.

    Make sure to carry some snacks to your physicians office so that you can eat immediately after blood is drawn. Blood glucose for postprandial levels requires you to eat and give a blood sample after an hour of a meal.

    Hopefully, this article has given you a good idea about fasting for blood tests and which blood tests require fasting. These questions should additionally be clarified with your physician. This is because your physician will be able to guide you better.

    Medically Reviewed By

    Dr. Himanshi is a Homoeopathic consultant and currently working as a lecturer in Post-graduate faculty of Homeopathy, Parul University, Vadodara. Completed BHMS and MD in Homeopathy in January 2018 and also has a clinical experience of about 6 years. Personal interests include reading, spending time with family and traveling.

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    Tests For Blood Sugar And Hba1c

    In this series

    Blood sugar measurements are used to diagnose diabetes. They are also used to monitor glucose control for those people who are already known to have diabetes.

    In this article

    Tests for Blood Sugar and HbA1c

    In this article

    If your glucose level remains high then you have diabetes. If the level goes too low then it is called hypoglycaemia.

    The main tests for measuring the amount of glucose in the blood are:

    • Random blood glucose level.
    • Capillary blood glucose .
    • Urine test for blood sugar .

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

    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.

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    How To Measure Your A1c At Home

    The A1C or Hemoglobin A1C test is something everyone living with diabetes should be familiar with.

    It doesnt show the whole picture of your diabetes management, but it can be a great indicator of whether your average blood sugar levels are within a healthy range.

    Today, Ill show you how to easily and accurately measure your A1C at home.

    Well also discuss what an A1C test actually tells you, why its a relevant test, and how to interpret the results.

    A1c Results And What The Numbers Mean

    Diabetes Blood Test Results Explained | A1C and Fasting Blood Sugar
    *Any test used to diagnose diabetes requires confirmation with a second measurement, unless there are clear symptoms of diabetes.

    Diagnosis*
    Diabetes 6.5 percent or above

    When using the A1C test for diagnosis, your doctor will send your blood sample taken from a vein to a lab that uses an NGSP-certified method. The NGSP, formerly called the National Glycohemoglobin Standardization Program, certifies that makers of A1C tests provide results that are consistent and comparable with those used in the Diabetes Control and Complications Trial.

    Blood samples analyzed in a doctors office or clinic, known as point-of-care tests, should not be used for diagnosis.

    The A1C test should not be used to diagnose type 1 diabetes, gestational diabetes, or cystic fibrosis-related diabetes. The A1C test may give false results in people with certain conditions.

    Having prediabetes is a risk factor for developing type 2 diabetes. Within the prediabetes A1C range of 5.7 to 6.4 percent, the higher the A1C, the greater the risk of diabetes.

    Also Check: Did Intermittent Fasting Work For You

    Random Blood Sugar Test

    This measures your blood sugar at the time youre tested. You can take this test at any time and dont need to fast first. A blood sugar level of 200 mg/dL or higher indicates you have diabetes.

    Random Blood Sugar Test

    140 mg/dL or below ;N/A

    *Results for gestational diabetes can differ. Ask your health care provider what your results mean if youre being tested for gestational diabetes.Source: American Diabetes Association

    If your doctor thinks you have type 1 diabetes, your blood may also tested for autoantibodies that are often present in type 1 diabetes but not in type 2 diabetes. You may have your urine tested for ketones , which also indicate type 1 diabetes instead of type 2 diabetes.

    Why Is It Important To Measure Your A1c

    Since elevated blood sugars can lead to a number of short- and long-term complications, its advisable to keep an eye on your A1C and ensure that its held at a healthy level.

    If you find that your blood sugars are increasing above your target, there are several things you can do to reduce them, such as discussing adjusting your medication with your doctor, changing your diet, and making lifestyle changes

    You can read our complete guide to lowering your A1C for more information.

    Since the A1C tests give you a picture of your blood sugar level for the last 3 months, it makes sense to have your A1C measured at least every 3 months to keep track of how your blood sugars are progressing.

    It the test is used for a diabetes diagnosis, you might have to also have your fasting blood sugar and antibody levels measured to determine which type of diabetes you live with, such as type 1 or type 2 diabetes.

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    Why Should A Person Get The A1c Test

    Testing can help health care professionals

    • find prediabetes and counsel you about lifestyle changes to help you delay or prevent type 2 diabetes
    • find type 2 diabetes
    • work with you to monitor the disease and help make treatment decisions to prevent complications

    If you have risk factors for prediabetes or diabetes, talk with your doctor about whether you should be tested.

    Setting Goals For A1c Levels

    Translating Your A1c to a Blood Sugar Level

    The target A1c level for people with diabetes is usually less than 7%. The higher the hemoglobin A1c, the higher your risk of having complications related to diabetes. Someone who has had untreated diabetes for a long time might have a level above 8%.

    If you have diabetes and your level is above your target, your doctor may change your treatment plan to get your level down.

    A combination of diet, exercise, and medication can bring your levels down.

    People with diabetes should have an A1c test every 3 months to make sure their blood sugar is in their target range. If your diabetes is under good control, you may be able to wait longer between the blood tests. But experts recommend checking at least two times a year.

    People with diseases affecting hemoglobin, such as anemia, may get misleading results with this test. Other things that can affect the results of the hemoglobin A1c include supplements such as vitamins C and E and high cholesterol levels. Kidney disease and liver disease may also affect the test.

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