Glucose Tolerance Test Part- II.pptx

Oral glucose tolerance tests (OGTT) are used to measure how well the body can process a larger amount of sugar.

1. Glucose Tolerance Test Mr. Abhijit Bhoyar Assistant Professor Department of Child Health Nursing Part-II

2. Specific Learning Objectives At the end of the lecture, the students will be able to Explain Intravenous Glucose Tolerance Test. ( IV GTT). Describe Mini or Modern Glucose Tolerance Test ( GTT) . Explain the Extended Glucose Tolerance Test ( GTT) . Describe the Glucose Challenge Test ( GCT ) . Explain the Hemoglobin A1C (HbA1c) Test .

3. Introduction Intravenous Glucose Tolerance Test. (IV GTT). Mini or Modern Glucose Tolerance Test ( GTT) . Extended Glucose Tolerance Test ( GTT) . Glucose Challenge Test ( GCT) . Hemoglobin A1C (HbA1c) Test.

4. Intravenous Glucose tolerance tes t Definition Intravenous Glucose Tolerance Test (IVGTT )   a method to estimate insulin sensitivity based on intravenous glucose infusion .

5. Indication This test is undertaken for patients with malabsorption (Celiac disease or enteropathies). Under these conditions oral glucose load is not well absorbed and the results of oral glucose tolerance test become inconclusive.

6. I/V Glucose tolerance test- Procedure I/V glucose tolerance test is carried out by giving 25 g of glucose dissolved in 100 ml distilled water as intravenous injection within 5 minutes. Completion of infusion is taken as time zero. Blood samples are taken at 10 minutes interval for the next hour. The peak value is reached within a few minutes.

7. I/V Glucose tolerance test Interpretation Normally , blood glucose level returns to normal range within 60 minutes. In diabetes mellitus, this decline is slow.

8. Mini or Modern GTT As per current WHO recommendations, in the mini or modern glucose tolerance test, only two samples are collected. Fasting (zero hour) and 2 hour post glucose load. Urine samples are also collected during the same time. The diagnosis is made from the variations observed in these results.

9. Cont.…. Zero Hour After 2 Hours Normal Person < 110 mg/ dL < 140 mg/ dL Increase Glucose tolerance 110 – 126 mg/ dL 140 – 199 mg/ dL

10. GTT Under special conditions Cortisone stress test- used for detecting pre diabetes or Latent diabetes Extended GTT- To diagnose the cause of hypoglycemia especially 2-3 hours after meals.

11. Criteria for diagnosis Of DM If the fasting plasma glucose level is 126 mg/ dL or higher on more than one occasion, further evaluation of the patient with a glucose challenge is unnecessary. However , when fasting plasma glucose is less than 126 mg/ dL in suspected cases, a standardized oral glucose tolerance test may be done .

12. Cont.…. A random plasma glucose concentration >11.1 mmol /L (200 mg/ dL ) accompanied by classic symptoms of DM (polyuria, polydipsia, weight loss) is sufficient for the diagnosis of DM.

13. Extended glucose tolerance test It may be conducted to detect cases of reactive hypoglycaemia ( Reactive hypoglycemia (postprandial hypoglycemia) refers to low blood sugar that occurs after a meal — usually within four hours after eating ) or other abnormalities of glucose metabolism with samples taken at 0, 30, 60, 90, 120, 150 and 180 minutes . The extended test may also be used to diagnose acromegaly when samples are also taken for growth hormone levels.

14. Preparation Glucose solution is best prepared in advance as glucose dissolves better in warm water but is more palatable when cold. On the day prior to the test, dissolve 75 grams of anhydrous glucose in warm water and store in a fridge overnight. The patient must be fasted from midnight (sips of water only).

15. Procedure Check that the patient has fasted from midnight. Insert an indwelling cannula gauge 20 with a three-way tap. Using the vacutainer connector system or a syringe, fill a fluoride oxalate bottle with 2mls of blood, label the tube with time=0, and test a small sample using a glucose meter. Give the patient the glucose solution to drink (within 10 minutes).

16. Cont…. Take a further blood sample, test it using a glucose meter, and place the rest of the sample into a fluoride oxalate bottle at 30, 60, 90, 120, 150, 180, 240 minutes (total test time four hours). If any glucose meter readings are below 3.0mmol/l during the test, take two further samples at 270 and 300 minutes. Record any symptoms the patient has with the times in the notes.

17. The Glucose Challenge Test The glucose challenge test, also called the one-hour glucose tolerance test, measures body's response to sugar (glucose). It is done during pregnancy to screen for gestational diabetes — diabetes that develops during pregnancy. The test is done in two steps.

18. Cont.…. First drink a sugary solution. One hour later, blood sugar level is measured. The results indicate whether pregnant leady might have gestational diabetes. If the test results are outside the standard range, you might need further testing to determine the diagnosis.

19. Indications S creen for gestational diabetes during pregnancy- screened during your second trimester — between 24 and 28 weeks of pregnancy .

20. Procedure The glucose challenge test is done in two steps. Then drink a syrupy glucose solution that contains 1.8 ounces (50 grams) of sugar. blood sugar level to be tested. Patient can't eat or drink anything other than water at this point. One hour later, a blood sample will be taken from a vein in patients arm to measure blood sugar level.

21. Results Results of the glucose challenge test are given in milligrams per deciliter (mg/ dL ) or millimoles per liter ( mmol /L). A blood sugar level below 140 mg/ dL  (7.8  mmol /L) is considered standard.

22. Cont…. A blood sugar level of 140 mg/ dL  (7.8  mmol /L) to less than 190 mg/ dL  (10.6  mmol /L) indicates the need for a three-hour glucose tolerance test to diagnose gestational diabetes. A blood sugar level of 190 (10.6  mmol /L) or higher indicates gestational diabetes . Further testing might not be needed.

23. Hemoglobin A1C (HbA1c) Test A hemoglobin A1c (HbA1c) test measures the amount of blood sugar (glucose) attached to hemoglobin. Hemoglobin is the part of red blood cells that carries oxygen from lungs to the rest of your body.

24. Cont…. An HbA1c test shows what the average amount of glucose attached to hemoglobin has been over the past three months. It's a three-month average because that's typically how long a red blood cell lives.

25. Cont….. If HbA1c levels are high, it may be a sign of diabetes, a chronic condition that can cause serious health problems, including heart disease, kidney disease, and nerve damage. Other names: HbA1c, A1c, glycohemoglobin, glycated hemoglobin, glycosylated hemoglobin

26. R esults Normal : HbA1c below 5.7% Prediabetes : HbA1c between 5.7% and 6.4% Diabetes : HbA1c of 6.5% or higher

27. Expected Questions Short Explain Intravenous Glucose Tolerance Test. (IV GTT). Describe Mini or Modern Glucose Tolerance Test (GTT) . Explain the Extended Glucose Tolerance Test (GTT) . Describe the Glucose Challenge Test (GCT) . Very Short Define Hemoglobin A1C (HbA1c) Test.

28. References Jacob Anthikad, Biochemistry for nurses 3 rd ed. Pankaja Naik, Essentials of Biochemistry, 1 st ed. Satyanarayan, Essentials of Biochemistry, 2 nd ed. A. C. Deb, Biochemistry, 4 th ed.

29. THANK YOU