Glucose Tolerance Test : Diagnosis-Benefits


 What Is a Glucose Tolerance Test?

Glucose tolerance takes a look at manners to assess the potential of the frame to metabolize glucose, the foremost sort of sugar determined in the blood.

In men and women with everyday or barely multiplied blood-sugar stages, the body tolerance to sugar is measured in a disturbing situation brought about through administering a large amount of glucose. The most commonplace procedure is to take a preliminary blood sample from a fasting character, have the man or woman empty his or her bladder, and then administer orally 50–100 grams of glucose (commonly 1 gram of glucose consistent with kilogram of ideal frame weight) dissolved in water. Samples of blood and urine for glucose determination are obtained half-hour, 1 hour, 2 hours, and 3 hours later. Normally the awareness of glucose in the blood will upward thrust to approximately a hundred and forty mg/one hundred ml within 45–60 mins and will go back in 1 half of–2 1/2 hours to the regular range of 80–a hundred and twenty mg/100 ml. The most valuable diagnostic factor is two hours, whilst the fee needs to be less than one hundred twenty mg/a hundred ml.

A fasting glucose tolerance check can convey important data about the approximately decreased tolerance to sugar in individuals tormented by an impairment of sugar metabolism, together with diabetes mellitus. In these individuals a reduced tolerance to sugar is manifested with the aid of a blood-sugar-stage curve that rises better than, and returns extra slowly to, everyday. This type of curve will also be visible in nondiabetic persons for the duration of acute illness, after trauma, or while on a low-carbohydrate eating regimen; it may additionally be located in elderly humans with hardening of the arteries or coronary heart sickness and in middle-aged humans who are markedly overweight.

An oral glucose tolerance test is used to verify or exclude the analysis of diabetes mellitus while a fasting blood glucose test end result isn't definitive (i.E., greater than the higher variety of the normal fee but less than the diagnostic level for diabetes). Even if a blood glucose test is received after fasting 10–12 hours and the level is above 140 mg/100 ml, it's crucial to verify the result with a 2nd determination to rule out different elements which can have given a one-time atypical take a look at the end result.

The oral glucose tolerance check measures the response of the frame to a project load (a quantity calculated to rouse a response) of glucose. It most usually is used during being pregnant to locate early glucose intolerance that would pose a big danger to the infant if the circumstance advanced to gestational diabetes mellitus. After a fasting blood glucose test end result has been acquired, 75 grams of glucose (100 g if the affected person is pregnant) is run and blood samples are taken every half-hour for 2 hours. In patients with diabetes, the blood glucose cost will upward push to a higher degree and continue to be better longer than in those who do not have diabetes.

A less difficult but less-reliable screening check is the 2-hour postprandial blood glucose test. This check is finished 2 hours after intake of a preferred glucose answer or a meal containing a hundred grams of carbohydrates. A plasma glucose level above 140 mg/a hundred ml suggests the need for a glucose tolerance take a look at.

The glucose tolerance take a look at, additionally known as the oral glucose tolerance take a look at, measures your frame's response to sugar (glucose). The glucose tolerance taken a look at can be used to display for kind 2 diabetes. More normally, a modified model of the glucose tolerance test is used to diagnose gestational diabetes — a type of diabetes that develops in the course of pregnancy.

Why is a glucose tolerance test performed?

The glucose tolerance check identifies abnormalities inside the manner your body handles glucose after a meal — frequently before your fasting blood glucose level will become unusual.The glucose tolerance taken a look at is one way to evaluate how nicely your frame metabolizes glucose. Your physician may also have several distinctive reasons for recommending this check:

  • Diagnosing prediabetes and diabetes: Diagnosis is the technique of determining what's inflicting modifications in your health which you or your health practitioner may also have located. The glucose tolerance test may be ordered in case you are displaying signs or signs of diabetes, specially if different checks for diabetes are inconclusive.

  • Screening for prediabetes and diabetes: Screening is checking for a disease before it reasons signs and signs and symptoms. Your doctor may additionally need you to be screened for diabetes if you are over 45 years old or are at an extra-than-common danger of the disease. In fashion, different kinds of diabetes assessments are more usually used for screening than the glucose tolerance. Take a look at. However, the glucose tolerance test is frequently used to display screens for diabetes in pregnant women.

  • Screening for and diagnosing gestational diabetes: Gestational diabetes is a shape of diabetes that could increase in ladies while they're pregnant. If you are pregnant, your health practitioner may advocate this testing, that is defined in our manual to Glucose Tests for Gestational Diabetes.

Risks Glucose Tolerance Test

The risks related to obtaining a blood pattern are slight. After your blood is drawn, you may revel in bruising or bleeding. You may additionally experience dizziness or lightheadedness. In a few cases, infection after your manner is feasible.

Side consequences include:

  • Nausea

  • Vomiting

  • Bloating

  • Headache

  • Low blood sugar 

  • Excess bleeding

  • Fainting

  • Infection

Prepare for the procedure Glucose Tolerance Test

You will be required to rapid for at least 8 hours earlier than you're taking the check. This manner you may need to go with no food or any drink except water. Since the test is often scheduled for the morning, maximum of your fasting can show up whilst you sleep the night earlier than.

You can typically follow an ordinary food regimen up till the time you begin fasting. Your medical doctor may ask you to make certain you eat at least a hundred and fifty grams of carbohydrates every day three days earlier than your glucose tolerance check.

If you are taking any prescription medicinal drugs or over the counter pills, make certain to discuss these with your physician before you are taking a look at. Your medical doctor can permit you to recognise whether any of those might adjust the outcomes of the test. They can also ask you whether you'll need to forego taking any medications all through the time you are fasting.

To make sure the maximum dependable effects, ask your physician for any particular pretest preparations and thoroughly observe the ones instructions on the days main up in your glucose tolerance check.

Food and medications

It's vital to eat and drink commonly within the days leading up to the glucose tolerance take a look at. Let your health practitioner recognise in case you're sick or taking any medications, as these elements can have an effect on the effects of your test.

What you can expect Glucose Tolerance Test

During the procedure Glucose Tolerance Test

The glucose tolerance taken a look at is finished in numerous steps. When you arrive at your medical doctor's office or lab, a member of your health care crew will take a sample of blood from a vein on your arm. This blood sample can be used to degree your fasting blood glucose stage.

Glucose tolerance testing usually takes place within the morning. You may additionally want to stay at the checking out web page for up to a few hours.

The phlebotomist who offers you the test will begin by means of drawing a small quantity of your blood from a vein, most usually for your arm. The technician may tie a band round your top arm so the vein is less difficult to see. After cleaning the pores and skin over your vein with a sterile wipe, a small needle will be inserted via the skin and into the vein. The sample of blood is going right into a tube attached to the needle.

When the needle comes out, the phlebotomist will launch the band on your arm and cover the injection web site with a small bandage. Some people experience minor ache or pain whilst the needle goes in or comes out, however this usually does not remain very lengthy.

Once the first blood pattern is taken, you'll drink a bottle of liquid containing a defined quantity of glucose. In adults, the drink normally includes 75 grams of glucose. In kids, the quantity is calculated based totally on frame weight with a maximum of seventy five grams. This drink tastes sweet like a sugary soda.

After you drink the glucose solution, your blood may be drawn numerous greater times at regular intervals over the following two or 3 hours. You must now not devour some thing at some stage in this time, and also you commonly will continue to be within the waiting location.

Type 2 diabetes - Glucose Tolerance Test

 tested for type 2 diabetes:

  • You'll drink about 8 ounces (237 milliliters) of a syrupy glucose solution containing 2.6 ounces (75 grams) of sugar

  • Two hours later, your blood glucose level will be measured again

Gestational diabetes - Glucose Tolerance Test

The American College of Obstetricians and Gynecologists recommends performing a one-hour blood glucose undertaking take a look at to display for gestational diabetes in low-risk pregnant girls between 24 and 28 weeks of pregnancy.

Your health practitioner might also endorse earlier screening in case you're at elevated hazard of developing gestational diabetes. Risk factors can also include:

If your physician determines you're at risk or you have a suspicious price on the only-hour test, you may be counseled to take a 3-hour glucose tolerance test.

For the three-hour test:

  • You may be asked to return to take a look at fasting — now not having had whatever to eat or drink for the preceding 8 hours. A fasting blood sugar may be received.

  • You'll drink about 8 ounces (237 milliliters) of a glucose solution containing 3.5 ounces (100 grams) of sugar.

  • Your blood glucose degree will be tested once more one,  and 3 hours when you drink the solution.

After consuming the glucose solution, you may in all likelihood need to remain within the physician's office or lab whilst you are looking ahead to your blood glucose degree to be tested.

After the procedure Glucose Tolerance Test

After the series of blood attracts is whole, you can enjoy moderate ache in which the blood changed into taken. You can usually resume ordinary activities after your glucose tolerance test is achieved. When the take a look is completed, you will be capable of eating once more. You may wish to take a snack with you to the trying out website online to have on hand after your final blood draw is finished.

After the glucose tolerance test, you may return to your normal sports right now.


Results of the oral glucose tolerance test are given in milligrams consistent with deciliter (mg/dL) or millimoles in step with liter (mmol/L).

You will commonly get the consequences of your glucose tolerance test some commercial enterprise days after you are taking the check. You may be capable of getting entry to your check consequences online, or you may get hold of results through email or through postal mail. Your health practitioner might also attain out by using phone or email to speak about the test consequences or may additionally agenda an appointment to go over the results in individual.

Type 2 diabetes

If you're being tested for type 2 diabetes, two hours after drinking the glucose solution:

  • A normal blood glucose level is lower than 140 mg/dL (7.8 mmol/L).

  • A blood glucose degree between a hundred and forty and 199 mg/dL (7.8 and eleven mmol/L) is taken into consideration impaired glucose tolerance, or prediabetes. If you have got prediabetes, you're prone to finally developing type 2 diabetes. You're additionally susceptible to growing heart disease, even in case you don't develop diabetes.

  • A blood glucose level of 200 mg/dL (11.1 mmol/L) or higher may indicate diabetes.

If the results of your glucose tolerance take a look at indicate kind 2 diabetes, your physician might also repeat the take a look at on another day or use any other blood check to confirm the analysis. Various factors can have an effect on the accuracy of the glucose tolerance check, which includes infection, activity stage and positive medicinal drugs.

Gestational diabetes

If you're being tested for gestational diabetes, your medical doctor will not forget the effects of each blood glucose take a look at.

If your blood glucose level is higher than one hundred forty mg/dL (7.8 mmol/L) after the only-hour check, your health practitioner will advise the three-hour check. If your blood glucose stage is better than one hundred ninety mg/dL (10.6 mmol/L) after the one-hour check, you may be identified with gestational diabetes.

For the 3-hour test:

  • A normal fasting blood glucose level is lower than 95 mg/dL (5.3 mmol/L).

  • One hour after drinking the glucose solution, a normal blood glucose level is lower than 180 mg/dL (10 mmol/L).

  • Two hours after drinking the glucose solution, a normal blood glucose level is lower than 155 mg/dL (8.6 mmol/L).

  • Three hours after drinking the glucose solution, a normal blood glucose level is lower than 140 mg/dL (7.8 mmol/L).

If one of the results is higher than regular, you will possibly want to test again in 4 weeks. If more of the results are higher than ordinary, you'll be identified with gestational diabetes.

If you are diagnosed with gestational diabetes, you can save you headaches by cautiously handling your blood glucose stage during the rest of your pregnancy.

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