ORAL GLUCOSE TOLERANCE TEST.pptx slides presentation

Talk on glucose

1. ORAL GLUCOSE TOLERANCE TEST BY DR.MOHAMMED MANU DEPARTMENT OF CHEMICAL PATHOLOGY ABUTH,ZARIA.

2. CONTENT Introduction. Indication for Oral Glucose Tolerance Test. Patient Preparation. Test Procedure. Interpretation of results. Factors affecting the test. Disadvantages of the test. Conclusion. References.

3. INTRODUCTION Oral Glucose Tolerance Test(OGTT) was introduced in 1913, and remains the most definitive test for the diagnosis of diabetes mellitus. The OGTT measures the ability of the body to tolerate, or cope with a standard dose of glucose. The degree of tolerance to the glucose, as shown by a change in the blood level, is mainly dependent on the rate of glucose absorption and insulin response .

4. CONT.. As the glucose is absorbed, the level of glucose in the blood rises and the normal response is for insulin to be released from the β cells of the Pancreas to lower the glucose level. Tolerance is reduced when insulin is insufficient or absent.

5. INDICATION Equivocal glucose results that cannot establish or exclude diabetes mellitus. Diagnosis of Gestational Diabetes mellitus. Diagnosis of Impaired Glucose Tolerance. Diagnosis of Acromegaly . Diagnosis of Reactive hypoglycaemia . Population studies for epidemiological data.

6. PATIENT PREPARATION 1.Adequate explanation on the purpose and procedure of the test. 2.The test should not be done during an illness, as results may not reflect the patients glucose metabolism when healthy. 3.The Patient should be on unrestricted diet containing about 150-250g Carbohydrate per day for three days. 4.There should be unrestricted usual physical activity.

7. CONT.. 5.An overnight fast of 8-14 hours during which only water can be taken. 6.Restriction of Drugs known to influence blood glucose levels( e.g Thiazide diuretic, Oral contraceptives, Corticosteriods etc).

8. TEST PROCEDURE - The Patient should sit quietly for about 30 minutes prior to and during the test, with no exercise or smoking allowed. A fasting blood and Urine samples (zero time or baseline) are collected after which the patient is given 75g of glucose in 250-300ml water to be drunk within 5minutes. Further blood and Urine samples are collected at 60, 120 and180 minutes after the oral glucose administration.

9. PROCEDURE IN GESTATIONAL DIABETES 1 .One step approach(using 75g or 100g glucose). 2 .Two step approach. A. Screening step -50g glucose is given irrespective of time of day or time of last meal. -Measure glucose at one hour. -If plasma glucose is ≥ 139mg/dl perform glucose tolerance test. B. Diagnostic step

10. DOSE OF GLUCOSE AND VARIATION In the US, dosing is by weight, and since the late 1970s it has been 1.75 grams of glucose per kilogram of body weight , to a maximum dose of 75g. The WHO recommendation is for a 75g oral dose in all adults and the dose is adjusted for weight in children.

11. CONT.. In UK General Practice, the standard glucose load is provided by 394ml of the sports drink Lucozade (original flavour only), which the patient is asked to supply.

12. AMERICAN DIABETIC ASSOCIATION CRITERIA-2005 (Interpretation of OGTT) NORMAL 1GT IFG DM FPG 5.5mmol/L (99mg/dl) <7.0mmol/L (<126mg/dl) 5.6-6.9mmol/L (100-125mg/dl ≥7.0mmol/L ≥ 126mg/dl 2 HOUR <7.8mmol/L (<140mg/dl) 7.8-11.1mmol/L (140-199mg/dl <7.8mmol/L (140mg/dl) ≥11.1mmol/L ≥ 200mg/dl

13. 1999-WHO CRITERIA (Interpretation of OGTT) NORMAL IFG IGT DM FPG <6.1mmol/L (<110mg/dl) 6.1-7.0mmol/L (110-125mg/dl <7.0mmol/L (<126mg/dl) ≥ 7.0mmol/L (≥ 126mg/dl) 2 HOURS <7.8mmol/L (<140mg/dl) <7.8mmol/L (<140mg/dl) 7.8-11.1mmol/l (140-200mg/dl >11.1mmol/L (>200mg/dl) NORMAL IFG IGT DM FPG <6.1mmol/L (<110mg/dl) 6.1-7.0mmol/L (110-125mg/dl <7.0mmol/L (<126mg/dl) ≥ 7.0mmol/L (≥ 126mg/dl) 2 HOURS <7.8mmol/L (<140mg/dl) <7.8mmol/L (<140mg/dl) 7.8-11.1mmol/l (140-200mg/dl >11.1mmol/L (>200mg/dl)

14. AMERICAN DIABETIC ASSOCIATION(2005)CRITERIA -GESTATIONAL DIABETES 100g load 75g load Fasting 5.3mmol/L(95mg/dl) 5.3mmol/L(95mg/dl) 1 Hour 10mmol/L(180mg/dl 10mmol/L(180mg/dl) 2 Hour 8.6mmol/L(155mg/dl) 8.6mmol/L(155mg/dl) 3 Hour 7.8mmol/L(140mg/dl) -

15. NORMAL CURVE FBG-<100mg/dl, 2 HOURS-<100mg/dl

16. IMPAIRED GLUCOSE TOLERANCE FBG-100mg/dl,2 HOURS-140mg/dl

17. DIABETES MELLITUS FBG->200mg/dl, 2 HOURS-300mg/dl

18. LAG CURVE

19. FLAT CURVE

20. RENAL GLYCOSURIA

21. FACTORS AFFECTING OGTT 1.Patient Preparation - Duration of fast. -Prior Carbohydrate intake. -Medications. -Trauma. - Intercurrent illness. -Activity.

22. CONT. 2.Administration of Glucose -Form of glucose. -Quantity of glucose ingested. -Volume in which administered. -Rate of ingestion. 3.During the test -Anxiety -Caffeine.

23. CONT.. -Smoking. -Activity. -Time of day(glucose tolerance has diurnal rhythm.

24. DISADVANTAGES OF OGTT The procedure is tedious for patient as well as for medical and laboratory staff. The procedure is expensive in terms of high skill requirement.

25. CONCLUSION Oral Glucose Tolerance Test even though a tedious and expensive procedure remains the definitive test in the diagnosis of Diabetes mellitus and Gestational diabetes.

26. REFERENCES H.S.Isah , Essential Clinical Biochemistry. Tamaza Publishing Company Limited. M.A.Crook,Clinical Biochemistry and Metabolic Medicine.International Students’ Edition. M.Cheesbrough,District Laboratory Practice in Tropical Countries.Second Edition Part One. Carl A.B, Edward R.A, David E.B. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, 4 th edition.

27. CONT. http://www.nlm.nih.gov/medlineplus/ency/article/003466.htm . American Diabetes Association. Standards of medical care in diabetes--2013. Diabetes Care . 2013 Jan;36 Suppl 1:S11-66. http://en.wikipedia.org/wiki/file:acromegaly_facial_features.JPEG.

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