Glucose Tolerance Test Overview
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Glucose Tolerance Test Overview

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Questions and Answers

What does a glucose tolerance test primarily assess?

  • Liver function
  • Insulin production
  • The total blood volume
  • The body's ability to utilize carbohydrates (correct)

    • What occurs in conditions of insulin deficiency during a glucose tolerance test?

  • Blood glucose levels decrease significantly
  • Blood glucose levels remain constant
  • Blood glucose levels normalize quickly
  • Blood glucose levels get elevated (correct)

    • Which of the following conditions is associated with increased glucose tolerance?

  • Diabetes mellitus
  • Hyperinsulinism (correct)
  • Adrenal cortical hypofunction
  • Hypopituitarism

    • When is a glucose tolerance test indicated for asymptomatic individuals?

    <p>With sustained or transient glycosuria</p> Signup and view all the answers

    What does decreased carbohydrate tolerance indicate?

    <p>Impaired utilization of carbohydrate loads</p> Signup and view all the answers

    What is one indication for performing a glucose tolerance test in patients with a family history?

    <p>If they have abnormal blood findings</p> Signup and view all the answers

    Which of the following is associated with decreased glucose tolerance?

    <p>Hypothyroidism</p> Signup and view all the answers

    Who might require a glucose tolerance test due to having a history of delivering large babies?

    <p>Women with gestational diabetes</p> Signup and view all the answers

    In which scenario is the glucose tolerance test not recommended?

    <p>In acutely ill patients</p> Signup and view all the answers

    What effect does hypothyroidism have on the glucose tolerance test?

    <p>Results in a flat glucose tolerance curve</p> Signup and view all the answers

    What should a patient avoid on the day of the glucose tolerance test?

    <p>Exercise and smoking</p> Signup and view all the answers

    What is the recommended fasting duration before a glucose tolerance test?

    <p>8-14 hours</p> Signup and view all the answers

    Which medication should be avoided prior to the glucose tolerance test?

    <p>Diuretics</p> Signup and view all the answers

    What is the purpose of collecting blood samples at half-hour intervals during the glucose tolerance test?

    <p>To observe changes in blood glucose over time</p> Signup and view all the answers

    What is the loading dose of glucose for an adult undergoing an oral glucose tolerance test?

    <p>75 g</p> Signup and view all the answers

    How is the normal glucose tolerance curve characterized after glucose load?

    <p>Rapid rise and rapid fall of glucose levels</p> Signup and view all the answers

    What is the fasting blood glucose level considered normal?

    <p>90 mg/dl</p> Signup and view all the answers

    Which statement about the peak blood glucose level after a glucose load is true?

    <p>The peak is typically reached after 1 hour.</p> Signup and view all the answers

    In an atypical normal response, what is the highest blood glucose level observed?

    <p>It does not exceed 160-180 mg/dl.</p> Signup and view all the answers

    What is a characteristic feature of a diabetic curve after glucose load?

    <p>Blood glucose level does not return to fasting level within 2.5 hours.</p> Signup and view all the answers

    At what time is the highest blood glucose value typically reached in diabetic patients?

    <p>Between 1-1.5 hours.</p> Signup and view all the answers

    When glucose is present in urine samples, what can be inferred about the blood glucose level?

    <p>Blood glucose exceeds the renal threshold.</p> Signup and view all the answers

    What happens to blood glucose levels in a normal glucose tolerance test after 150 minutes?

    <p>Levels return to normal.</p> Signup and view all the answers

    What is a common finding in urine for patients with diabetes?

    <p>Glucose detected consistently.</p> Signup and view all the answers

    Study Notes

    Glucose Tolerance Test

    • The glucose tolerance test (GTT) measures the body's response to sugar (glucose).
    • The GTT can be used to screen for type 2 diabetes.
    • The GTT also can be used to diagnose other conditions such as:
      • Hypoglycemia
      • Hyperglycemia

    Indications of Glucose Tolerance Test

    • Asymptomatic individuals with sustained or transient glycosuria.
    • Individuals with symptoms of diabetes but no glycosuria or hyperglycemia.
    • Family history of diabetes with no symptoms or positive blood findings.
    • Individuals with or without symptoms of diabetes mellitus with neuropathies or retinopathies.
    • Patients with unknown origin neuropathies or retinopathies.
    • Women with a history of delivering large babies or showing one abnormal blood finding.

    Contraindications of Glucose Tolerance Test

    • Proven cases of diabetes mellitus
    • Only recommended in doubtful cases—not for follow-up of the patient.
    • Should not be carried out in acutely ill patients.

    Factors Affecting GTT

    • Acute Infections: Cortisol is secreted, the curve is elevated and prolonged.
    • Hypothyroidism: A flat curve is obtained in hypothyroidism because thyroid hormone increases the absorption of glucose from the gut.
    • Starvation: There is a rise in counter-regulatory hormones, which show increased glucose tolerance.

    Some Precaution Before GTT

    • Subjects should be normally active and free from acute illness.
    • Medications that may impair glucose tolerance (e.g., diuretics, contraceptive drugs, glucocorticoids, niacin, phenytoin) should be avoided on the day of the test.
    • Patients should be on a carbohydrate-rich unrestricted diet for 3 days.
    • Patients should be ambulatory with normal physical activity.
    • Exercise, smoking, and tea or coffee are not allowed during the test period.
    • OGTT is carried out in the morning after the patient has fasted overnight for 8-14 hours.

    Preparing the Patient for GTT

    • A fasting venous blood sample is collected in the morning.
    • Patients ingest 75 g of anhydrous glucose in 250-300 ml of water over 5 minutes (for children, the dose is 1.75 g of glucose per kg).
    • In the classical procedures, blood and urine samples are collected at half-hourly intervals for the next three hours.
    • A curve is plotted with the blood glucose levels on the vertical axis against the time of collection on the horizontal axis.
    • The curve obtained is called the glucose tolerance curve.

    Interpreting the Glucose Tolerance Curve

    Normal Glucose Tolerance Curve

    • Fasting blood glucose (Zero-hour sample) is 90 mg/dl, which is within the normal range (Normal 60-100 mg/dl).
    • There is a rise in blood glucose after the glucose load, and the peak value is observed at 1 hour due to the absorption of glucose from the intestine.
    • Insulin is released upon an increase in blood glucose level.
    • There is a fall in blood glucose with time due to glucose utilization promoted by insulin.
    • The normal blood glucose level is achieved after 150 minutes.

    Diabetic Curve

    • Fasting blood glucose is higher than normal.
    • The highest value is attained at 1 hour to 1 hour and 30 minutes.
    • The highest value exceeds the renal threshold.
    • Glucose is found in almost all the urine samples.
    • The blood glucose level does not return to the fasting level even within 2 hours and 30 minutes.

    Response of Diabetic Patients in a Glucose Tolerance Test

    • Fasting blood glucose is definitely raised above 110 mg/dl.
    • The highest value is reached after 1-1.5 hours.
    • The highest value exceeds the renal threshold.
    • The blood glucose level does not return to the fasting level within 2.5 hours.
    • Urine samples always contain glucose except for some chronic diabetes or nephritis patients, who may have a raised renal threshold.

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    Related Documents

    Glucose Tolerance Test PDF

    Description

    This quiz covers the glucose tolerance test (GTT), detailing its purpose, indications, and contraindications. It is essential for screening type 2 diabetes and diagnosing related conditions. Test your knowledge about the GTT and its clinical relevance.

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