Wednesday, July 17, 2024

Should You Fast Before Glucose Test

Must read

How To Prepare 3 Hour Test

Fasting for a Blood Test: Dos and Dontâs

If your doctor would like to see additional testing, based on your results from the 1 hour test, you may be asked to have a 3 hour OGTT. It is important to follow all of the instructions very carefully, as it will affect the results of the test.

When you arrive at the office a sample or baseline glucose test will be run and used for comparing other glucose values. You will be asked to drink a sweet liquid containing a measured amount of glucose, it is best to drink it quickly. Then blood samples will be collected at timed intervals of 1,2, and 3 hours after you drink the glucose.

Here is the best method of preparation:

  • Eat a balanced diet that contains at least 150 grams of carbohydrates per day for 3 days before the test. Fruits, breads, cereal, rice, crackers, and starchy vegetables such as potatoes, beans and corn are good sources of carbohydrates.
  • Do not eat, drink, smoke, or exercise strenuously for at least 8 hours before your first blood sample is taken.
  • Tell your doctor about all prescription and nonprescription medicines you are taking. You may be instructed to stop taking certain medicines before the test.
  • The OGTT may take up to 4 hours. Since activity can interfere with test results, you will be asked to sit quietly during the entire test. Do not eat during the test. You may drink only water during this time.
  • Why Is A Fasting Blood Test Important

    Food, most drinks, and strenuous exercise can all lead to inaccurate blood test results. If the results of the blood test are unclear, the process will have to be completed again to get numbers that reflect your true state of health.

    In most cases, water may be consumed before a fasting blood test. If youre currently taking any medications, check with your doctor to see if you can take your regular dosage without affecting the results.

    Fasting actually affects the results of very few blood tests.

    For example, measurements of kidney, liver, and thyroid function, as well as blood counts, are not influenced by fasting.

    Fasting is required before commonly ordered tests for:

    • triglycerides
    • anaemia for accurate results.

    Tests For Gestational Diabetes

    Gestational diabetes is diagnosed using blood tests. Youll probably be tested between 24 and 28 weeks of pregnancy. If your risk is higher for getting gestational diabetes , your doctor may test you earlier. Blood sugar thats higher than normal early in your pregnancy may indicate you have type 1 or type 2 diabetes rather than gestational diabetes.

    You May Like: Whisky Or Brandy Which Is Good For Diabetes

    Your Glucose Test During Pregnancy: How To Pass It

    This post may contain affiliate links where I earn a small commission your purchase at no cost to you. Feel free to check my disclosure and terms for more info! Please note the advice on this site is general advice and you should consult a provider before making choices for yourself.

    If youre pregnant and expecting to have a glucose test as part of your prenatal care, you might be wondering how to prepare for the test. What can you eat and drink before the test? And what should you do on the day of the test? Keep reading for all the information you need to know about glucose tests during pregnancy.

    But first, how do I know all of this?

    Hi Im Hilary The Pregnancy Nurse . I have been a nurse since 1997 and I have 20 years of OB nursing experience, I am also the curly head behind Pulling Curls and The Online Prenatal Class for Couples. I even helped in a diabetes clinic during my 3rd pregnancy. I have helped LOTS of diabetic moms, and fielded lots of questions about the glucose test during pregnancy.

    Possibly, similarly important, I have taken the glucose test with my three pregnancies, and I understand your desire to PASS that test.

    First, lets chat a bit about what it is.

    What Abnormal Results Mean

    How Long Should You Fast Before Glucose Test

    Abnormal blood values for a 3-hour 100-gram oral glucose tolerance test are:

    • Fasting: greater than 95 mg/dL
    • 1 hour: greater than 180 mg/dL
    • 2 hour: greater than 155 mg/dL
    • 3 hour: greater than 140 mg/dL


    Abnormal blood values for a 2-hour 75-gram oral glucose tolerance test are:

    • Fasting: greater than 92 mg/dL
    • 1 hour: greater than 180 mg/dL
    • 2 hour: greater than 153 mg/dL

    If only one of your blood glucose results in the oral glucose tolerance test is higher than normal, your provider may simply suggest you change some of the foods you eat. Then, your provider may test you again after you have changed your diet.

    If more than one of your blood glucose results is higher than normal, you have gestational diabetes.

    Also Check: Purpose Of Insulin In The Body

    How Does Blood Glucose Work

    Blood sugar, or glucose, is the main sugar found in your blood. When you eat or drink, your body breaks down carbohydrates in the food or liquid into sugar for energy.

    Then your pancreas produces a hormone called insulin, which helps blood sugar enter your bodys cells. It also helps your body store blood sugar for later use. As the cells use the blood sugar, glucose and insulin levels in the blood decrease.

    But with diabetes, your body has trouble regulating glucose. Either your pancreas doesnt make enough insulin, or your body doesnt process insulin effectively. Therefore, the amount of sugar in your blood is higher than normal. And a lot of glucose in your blood is bad for your body.

    A fasting blood glucose test measures the amount of glucose in your blood when it should be at its lowest. That happens in the morning and when you havent had anything to eat or drink for a while.

    What Can I Expect On The Day Of The Test

    A fasting blood glucose test is often done with a common blood draw. A healthcare provider will:

    • Clean the area inside your elbow to kill any germs.
    • Tie a band around your upper arm, which will help the veins in your arm fill with blood.
    • Insert a clean needle into a vein .
    • Draw blood into a vial thats attached to the needle and labeled with your personal information.
    • Remove the band and then the needle.
    • Put pressure on the needle insertion site to stop the bleeding.
    • Place a bandage on the area.

    After the test, the healthcare provider will send the blood sample to a lab for testing.

    In some cases, your healthcare provider may be able to test your blood sugar with a prick on the finger instead of a needle in the vein. The provider uses a blood glucose monitor and test strip to measure your blood glucose level in the office.

    Recommended Reading: Diabetes And Vision Loss Symptoms

    What Is A Glucose Tolerance Test During Pregnancy And Why Is It Done

    A glucose tolerance test is usually done during the second trimester of pregnancy, between 24 and 28 weeks. However if you have certain risk factors, like weight, or having a previously large baby they may test you earlier .

    The test is used to screen for gestational diabetes, which is a type of diabetes that can develop during pregnancy.

    Gestational diabetes happens when your body cant make enough insulin to handle the extra glucose in your blood during pregnancy. Insulin is a hormone that helps your body use or store glucose for energy.

    For most women, gestational diabetes doesnt cause any noticeable symptoms. Thats why its important to get screened for the condition with a glucose tolerance test. If Gestational diabetes is not treated, it can lead to high blood sugar levels during pregnancy. This can cause problems for you and your baby, such as:

    -Preterm labor

    -Excessive weight gain in your baby

    -Increased risk of cesarean delivery

    -Breathing problems in your baby after birth

    I want to be really clear on the fact that most often there is no way for you to know if you have gestational diabetes. These women dont tend to feel much different than other pregnant women so taking this test is truly the only way!

    Hey, did you know that you are also at the perfect spot to take this too?

    Fasting Blood Sugar : Normal Levels And Testing

    Fasting before a blood test | What you know about fasting lab tests

    Fasting blood sugar levels give vital clues about how a person is managing their blood sugar. Blood sugar tends to peak about an hour after eating and declines after that.

    High fasting blood sugar levels point to insulin resistance or diabetes, while abnormally low fasting blood sugar could be due to diabetes medications.

    Knowing when to test and what to look for can help people stay healthy, especially if they have diabetes or are at risk of developing the condition.

    Keep reading to learn more about fasting blood sugar levels, including information on testing and tips for maintaining normal levels.

    The body needs glucose for energy, and glucose comes from the food a person eats. However, the body does not use all of this energy at once. Insulin makes it possible to store and release glucose as necessary.

    Following a meal, blood sugar levels rise and usually peak about an hour after eating.

    How high blood sugar rises and the precise timing of the peak depends on a persons diet.

    Food-related factors that can trigger significant rises include:

    • eating large meals
    • consuming sugary foods and drinks
    • eating foods with simple carbohydrates, or carbs, such as bread and sweet snacks

    As blood sugar rises, the pancreas releases insulin. Insulin lowers blood sugar, breaking it down so the body can use it for energy or store it for later.

    However, people who have diabetes have difficulties with insulin in one of two ways:

    Fasting blood sugar depends on three factors:

    Recommended Reading: Do Insulin Pens Need To Be Refrigerated

    Related: Pregnancy Test Very Faint Line : What Does It Mean

    We recommend that you still follow this list even after the glucose test, as this can manage your blood sugar levels to avoid such conditions. Besides what to eat, you can also follow these extra tips when taking your glucose test:

    • Schedule the test appointment in the morning to help make fasting easier
    • If youre thirsty, youre allowed to take small sips of water
    • Create a meal plan after the test or pack snacks in your bag to avoid feeling ravenous and lightheaded

    What Does The Glucose Tolerance Test Mean For Me After Baby

    Most often all the issues with blood sugar go away after the baby is born.

    Many hospitals will check your blood sugar the next day or so to see how it is doing, but likely you will be able to eat whatever you want.

    However, it does show that you are an increased risk of diabetes later in life, so consider making sure that you diet balances carbs and proteins, and make sure youre exercising to mitigate that risk.

    The reality is that much of this is genetic and we cant change that so changing what you can change is best.

    So, hopefully that gave you some ideas about this test. If youre interested in more information about your pregnancy and how to manage it successfully Id love to help you out in The Online Prenatal Class for Couples. Youre at the PERFECT SPOT to take it. Its offered on demand, and only takes a few hours.

    And, if youre not quite sure youre ready for that whole thing, check out my free prenatal class. Its your first step toward becoming your own birth boss.

    • About the Author

    Also Check: Diabetes Type 2 A1c Goals

    What Types Of Blood Tests Require Fasting

    The most common types of tests that require fasting include:

    • Glucose tests, which measure blood sugar. One type of glucose test is called a glucose tolerance test. For this test you will need to fast for 8 hours before test. When you arrive at the lab or health care facility, you will:
    • Have your blood tested
    • Drink a special liquid containing glucose
    • Have your blood re-tested one hour later, two hours later and possibly three hours later

    Glucose tests are used to diagnose diabetes.

    Glucose Screening Tests During Pregnancy

    How Long To Fast For Blood Glucose Test

    TWO-STEP TESTING During the first step, you will have a glucose screening test: You DO NOT need to prepare or change your diet in any way. You will be asked to drink a liquid that contains glucose. Your blood will be drawn 1 hour after you drink the glucose solution to check your blood glucose level. If your blood glucose from the first step is too high, you will need to come back for a 3-hour glucose tolerance test. For this test: DO NOT eat or drink anything for 8 to 14 hours before your test. You will be asked to drink a liquid that contains glucose, 100 grams . You will have blood drawn before you drink the liquid, and again 3 more times every 60 minutes after you drink it. Each time, your blood glucose level will be checked. Allow at least 3 hours for this test. ONE-STEP TESTING You need to go to the lab one time for a 2-hour glucose tolerance test. For this test: DO NOT eat or drink anything for 8 to 14 hours before your test. You will be asked to drink a liquid that contains glucose . You will have blood drawn before you drink the liquid, and again 2 more times every 60 minutes after you drink it. Each time, your blood glucose level will be checked. Allow at least 2 hours for this test.Continue reading > >

    Don’t Miss: Type 1 Diabetes And Eating Disorders

    When Can I Eat Or Drink Again

    As soon as your blood is taken, your fast is over. You might want to bring a snack and a drink with you so you can eat as soon as possible after the test.

    Show Sources

    American Academy for Clinical Chemistry: “Basic Metabolic Panel,” “Comprehensive Metabolic Panel,” “GGT,” “Glucose Tests,” “Iron Tests,” “Lipid Profile,” “Renal Function Panel,” “Vitamin B12 & Folate.”

    British National Health Service: “Can I Eat and Drink Before Having a Blood Test?”

    Crystal Moore, MD, PhD, FCAP, anatomical and clinical pathologist, Chesapeake, VA.

    National Heart Lung and Blood Institute: “What Are Blood Tests?”

    Nemours Foundation: “Blood Test: Comprehensive Metabolic Panel .”

    Providence Laboratory Services : “Fasting Instructions.”

    What Are Blood Glucose Tests Used To Diagnose

    Glucose testing is primarily done to diagnose or manage type 1 diabetes, type 2 diabetes, and gestational diabetes. Diabetes is a condition that causes your blood glucose levels to rise.

    The amount of sugar in your blood is usually controlled by a hormone called insulin. But if you have diabetes, your body either doesnt make enough insulin or the insulin produced doesnt work properly. This causes sugar to build up in your blood.

    If left untreated, chronically elevated levels of blood sugar can lead to other serious conditions including kidney disease, blindness, and heart disease.

    In some cases, blood glucose testing may also be used to test for hypoglycemia. This condition occurs when the levels of glucose in your blood are too low, usually lower than 70 milligrams per deciliter .

    Hypoglycemia can occur in people with diabetes if they take too much of their medication, like insulin, exercise more than usual, or skip a meal. Less commonly, hypoglycemia can be caused by other underlying conditions or medications.

    Doctors consider very low blood sugar to be a medical emergency, as it can lead to seizures, coma, and even death.

    Recommended Reading: Diabetic Diet Plan To Lose Weight

    What Is The Glucose Tolerance Test

    Prior to the taking the glucose tolerance test, your doctor will ask you to make sure and eat at least 150 mg of carbohydrates for three days prior to the time you will be asked to fast. You will not be permitted to eat or drink anything but sips of water for 14 hours prior to the test, so it is best to schedule the test for first thing in the morning.

    Additionally, you should plan to have someone drive you to and from the test since your energy levels may be low and there is a slight possibility you may feel light-headed.

    3-Hour Glucose Test

    When you arrive, the technician will draw blood to measure your baseline fasting blood glucose level. You will be asked to drink a larger volume of the glucose drink than was used in the initial Glucose Challenge Screening test. Your blood will be drawn and tested every hour for the next three hours.

    The following are the values that the American Diabetes Association considers to be abnormal during the Glucose Tolerance Test:


    How To Prepare For The 1

    When to Check Your Blood Sugar

    You dont need to do anything special to prepare for a glucose tolerance test. Just make sure you eat and drink normally in the days leading up to the test.

    On the day of the test, you may be asked to fast for a period of time before the test. You can usually drink water during this time.

    The time period where youre to fast before the test varies, so talk with your provider or the lab to make sure youre doing it to their specifications.

    You will likely have blood drawn before you take the glucose. This is to test how much sugar is in your blood when you havent eaten.

    Then, youll be asked to drink a sugary solution. The amount of sugar in the solution is about the same as in a can of soda. After you drink the solution, your blood will be drawn one or more times over the next hour.

    You might feel a little dizzy after drinking the sugary solution. This is normal. Just make sure you dont drive or operate machinery until the effects wear off.

    An hour after you drink that drink they will draw your blood again to see how your body is processing that sugar.

    Also Check: How To Take Diabetes Test

    More articles

    Popular Articles