Glucose Tolerance Test, 3 Specimens (75g) Most Popular

The following is a list of what is included in the item above. Click the test(s) below to view what biomarkers are measured along with an explanation of what the biomarker is measuring.

Also known as: Glucose Tolerance Test 3 Specimens 75g

1 Hour Specimen

2 Hour Specimen

Fasting Specimen

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The Glucose Tolerance Test, 3 Specimens (75g) test contains 1 test with 3 biomarkers.

Brief Description: The Glucose Tolerance Test, 3 Specimens, is a diagnostic test designed to evaluate how efficiently the body metabolizes glucose. It involves measuring blood glucose levels at multiple time points after the consumption of a high-glucose drink. This test helps diagnose various glucose-related disorders and assess the body's response to sugar intake.

Also Known As: Fasting Blood Glucose Test, FBG Test, Blood Sugar Test, Fasting Blood Sugar Test, FBS Test, Fasting Glucose Test, FG Test, Glucose Tolerance Test, GTT Test, Glucose 3 Specimen Test, Glucose 2 Hour Test, Glucose 1 hour Test, 3 Specimen Glucose Test

Collection Method: Blood Draw

Specimen Type: Serum

Test Preparation: Fasting required

When is a 3 Specimen Glucose Tolerance test ordered?

Diabetes screening is recommended by several health groups, including the American Diabetes Association and the United States Preventive Services Task Force, when a person is 45 years old or has risk factors.

The ADA recommends retesting within three years if the screening test result is within normal limits, but the USPSTF recommends testing once a year. Annual testing may be used to monitor people with prediabetes.

When someone exhibits signs and symptoms of high blood glucose, a blood glucose test may be conducted.

Diabetics are frequently asked to self-check their glucose levels multiple times a day in order to monitor glucose levels and choose treatment alternatives as suggested by their doctor. Blood glucose levels may be ordered on a regular basis, along with other tests such as A1c, to track glucose control over time.

Unless they show early symptoms or have had gestational diabetes in a prior pregnancy, pregnant women are routinely screened for gestational diabetes between the 24th and 28th week of pregnancy. If a woman is at risk of type 2 diabetes, she may be tested early in her pregnancy, according to the American Diabetes Association. When a woman has type 1, type 2, or gestational diabetes, her health care provider will normally order glucose levels to monitor her condition throughout the duration of her pregnancy and after delivery.

What does a 3 Specimen Glucose Tolerance blood test check for?

A Glucose Tolerance test measures glucose levels in your blood over a period of time through multiple specimen. Glucose is the major energy source for the body's cells and the brain and nervous system's only source of energy. A consistent supply must be provided, and a somewhat constant level of glucose in the blood must be maintained. The glucose level in the blood can be measured using a variety of methods. 

Fruits, vegetables, breads, and other carbohydrate-rich foods are broken down into glucose during digestion, which is absorbed by the small intestine and circulated throughout the body. Insulin, a hormone generated by the pancreas, is required for the use of glucose for energy production. Insulin promotes glucose transport into cells and instructs the liver to store surplus energy as glycogen for short-term storage or triglycerides in adipose cells.

Normally, blood glucose rises slightly after you eat or drink, and the pancreas responds by releasing insulin into the blood, the amount of which is proportional to the size and substance of the meal. The level of glucose in the blood declines as glucose enters the cells and is digested, and the pancreas responds by delaying, then ceasing the secretion of insulin.

When blood glucose levels fall too low, such as between meals or after a strong activity, glucagon is released, which causes the liver to convert some glycogen back into glucose, so boosting blood glucose levels. The level of glucose in the blood remains pretty steady if the glucose/insulin feedback loop is working appropriately. When the balance is upset and the blood glucose level rises, the body strives to restore it by boosting insulin production and removing excess glucose through the urine.

Several diseases can cause the equilibrium between glucose and pancreatic hormones to be disrupted, resulting in high or low blood glucose. Diabetes is the most common cause. Diabetes is a collection of illnesses characterized by inadequate insulin production and/or insulin resistance. Untreated diabetes impairs a person's ability to digest and utilize glucose normally. Type 1 diabetes is diagnosed when the body is unable to produce any or enough insulin. People with prediabetes or type 2 diabetes are insulin resistant and may or may not be able to produce enough of the hormone.

Organ failure, brain damage, coma, and, in extreme situations, death can result from severe, sudden fluctuations in blood glucose, either high or low. Chronically high blood glucose levels can harm body organs like the kidneys, eyes, heart, blood vessels, and nerves over time. Hypoglycemia can harm the brain and nerves over time.

Gestational diabetes, or hyperglycemia that exclusively arises during pregnancy, can affect some women. If left untreated, this can result in large babies with low glucose levels being born to these mothers. Women with gestational diabetes may or may not acquire diabetes later in life.

Lab tests often ordered with a 3 Specimen Glucose Tolerance test:

When a 3 Specimen GTT is ordered, it's often part of a broader evaluation of glucose metabolism and insulin function. Here are some tests commonly ordered alongside it:

  1. Hemoglobin A1c (HbA1c):

    • Purpose: To measure the average blood glucose levels over the past two to three months.
    • Why Is It Ordered: Provides a longer-term view of blood glucose control and is crucial for diagnosing and monitoring diabetes.
  2. Fasting Insulin Level:

    • Purpose: To measure the level of insulin in the blood while fasting.
    • Why Is It Ordered: To evaluate insulin production and resistance, especially if there is a suspicion of type 2 diabetes.
  3. C-Peptide Test:

    • Purpose: To measure C-peptide, a byproduct of insulin production.
    • Why Is It Ordered: To differentiate between type 1 and type 2 diabetes and to assess insulin production capacity.
  4. Complete Blood Count (CBC):

    • Purpose: To evaluate overall blood health.
    • Why Is It Ordered: To assess general health and rule out other conditions that might contribute to or mimic symptoms of diabetes.
  5. Lipid Profile:

    • Purpose: To measure levels of cholesterol and triglycerides.
    • Why Is It Ordered: To assess cardiovascular risk, as diabetes and dyslipidemia often coexist.
  6. Microalbumin:

    • Purpose: To detect small amounts of albumin in the urine.
    • Why Is It Ordered: To check for early signs of diabetic kidney disease.
  7. Thyroid Function Test:

    • Purpose: To assess thyroid function.
    • Why Is It Ordered: Because thyroid disorders can affect glucose metabolism and are more common in individuals with diabetes.
  8. Liver Function Test:

    • Purpose: To assess liver health.
    • Why Is It Ordered: To rule out liver diseases, as liver dysfunction can affect glucose metabolism.

These tests, when ordered alongside a 3 Specimen Glucose Tolerance Test, provide a comprehensive view of the body's glucose metabolism and insulin function. They are crucial for diagnosing various forms of diabetes, assessing insulin resistance, and identifying associated complications or comorbid conditions. The specific combination of tests will depend on the individual’s symptoms, risk factors, and overall health status.

Conditions where a 3 Specimen Glucose Tolerance test is recommended:

  • Gestational Diabetes: This test is frequently used during pregnancy to diagnose gestational diabetes, which can affect both the mother and the developing baby.

  • Prediabetes: Individuals with higher-than-normal blood sugar levels, but not yet meeting the criteria for diabetes, might undergo this test to determine if intervention is needed to prevent diabetes.

  • Diabetes Mellitus: The test helps confirm a diagnosis of diabetes by assessing how the body responds to glucose.

How does my health care provider use a 3 Specimen Glucose Tolerance test?

A blood glucose test can be used for a variety of purposes, including:

  • Detect hyperglycemia and hypoglycemia
  • Screen for diabetes in those who are at risk before symptoms appear; there may be no early indications or symptoms of diabetes in some circumstances. As a result, screening can aid in detecting it and allowing treatment to begin before the illness worsens or complications emerge.
  • Aid in the detection of diabetes, prediabetes, and gestational diabetes.
  • Monitor your blood sugar levels and manage your diabetes

Glucose levels should be monitored in those who have been diagnosed with diabetes.

Between the 24th and 28th week of pregnancy, glucose blood tests are performed to assess pregnant women for gestational diabetes. Pregnant women who have never been diagnosed with diabetes should be screened and diagnosed using either a one-step or two-step strategy, according to the American Diabetes Association and the US Preventive Services Task Force.

Other tests, including diabetic autoantibodies, insulin, and C-peptide, may be used in conjunction with glucose to assist in detecting the reason of elevated glucose levels, differentiate between type 1 and type 2 diabetes, and assess insulin production.

What do my glucose test results mean?

High blood glucose levels are most commonly associated with diabetes, but they can also be caused by a variety of other diseases and ailments.

Hypoglycemia is defined by a drop in blood glucose to a level that triggers nervous system symptoms before affecting the brain.

Most Common Questions About the Glucose Tolerance Test, 3 Specimens:

Purpose and Clinical Indications

What is the purpose of the Glucose Tolerance Test, 3 Specimens test?

The Glucose Tolerance Test, 3 Specimens test, is used to evaluate how the body handles glucose (sugar) after ingestion. It is commonly used to diagnose diabetes mellitus, prediabetes, and gestational diabetes.

What conditions can be diagnosed or ruled out with the Glucose Tolerance Test, 3 Specimens test?

This test is valuable in diagnosing Type 1 and Type 2 diabetes, gestational diabetes (in pregnancy), and insulin resistance or impaired glucose tolerance, a precursor to diabetes.

Methodology and Interpretation

How is the Glucose Tolerance Test, 3 Specimens test performed?

The patient fasts overnight, and a fasting blood sample is taken. Then, the patient consumes a sugary drink, and additional blood samples are taken at specified intervals, usually at 1 and 2 hours, making a total of 3 specimens.

How are the results of the Glucose Tolerance Test, 3 Specimens test interpreted?

The results are interpreted by comparing glucose levels at different time intervals to established reference ranges. Elevated glucose levels may indicate diabetes, while levels in a borderline range may suggest impaired glucose tolerance.

Can the Glucose Tolerance Test, 3 Specimens test differentiate between Type 1 and Type 2 diabetes?

The test does not directly differentiate between Type 1 and Type 2 diabetes but helps diagnose diabetes. Other clinical factors and tests are needed to determine the specific type.

Follow-up and Treatment

What are the next steps if the Glucose Tolerance Test, 3 Specimens test results indicate diabetes?

If diabetes is diagnosed, additional tests and evaluations may be necessary to tailor a management plan. This plan may include dietary adjustments, medications, exercise, and regular monitoring of glucose levels.

Miscellaneous Questions

How accurate is the Glucose Tolerance Test, 3 Specimens test?

The Glucose Tolerance Test, 3 Specimens test is considered highly accurate and reliable when performed under standardized conditions.

How do underlying illnesses or acute stress impact the Glucose Tolerance Test, 3 Specimens test?

Underlying illnesses or acute stress can affect blood glucose levels, potentially leading to misleading results. Therefore, any significant health changes should be communicated to the healthcare provider.

Can the Glucose Tolerance Test, 3 Specimens test be used to monitor diabetes treatment?

While it can be used to evaluate treatment effectiveness, it's typically not the primary method of monitoring diabetes treatment. Regular blood glucose checks and Hemoglobin A1c tests are more commonly used.

We advise having your results reviewed by a licensed medical healthcare professional for proper interpretation of your results.

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