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Glucose tolerance test
This document provides information about the glucose tolerance test (GTT), including: 1. The GTT measures a person's body's ability to utilize glucose by analyzing blood glucose levels after a glucose dose is administered orally or intravenously. 2. It can help diagnose prediabetes or diabetes, especially when symptoms are present but blood sugar levels are normal. It is also used during pregnancy to check for gestational diabetes. 3. The test involves fasting overnight, drinking a glucose dose, and having blood drawn every 30 minutes for 2.5 hours to analyze the blood glucose curve and see how quickly glucose is cleared from the bloodstream. Abnormal curves can indicate diabetes or other conditions.
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Glucose tolerance test
- 1. Glucose Tolerance Test (GTT) A s ho k K a t t a
- 2. What is GlucoseTolerance Test?
- 3. Glucose Tolerance GlucoseTolerance is the ability of the body to utilize glucose. GTT is indicated by the nature of blood glucose curve following the administration of glucose. Thus “Glucose Tolerance” is a valuable diagnostic aid. GTT can be performed by two ways…. Oral GTT Intravenous GTT
- 4. 1. In patientwith transient or sustained glycosuria, who have no clinical symptoms of diabetes with normal FBS &PPBS. 2. In patient with symptoms of diabetes but with no glycosuria and normal fasting blood glucose. 3. During pregnancy , excessive weight gaining is noticed, with a past history of big baby (> 4 kg ). 4. In persons with strong family history of Diabetes but no overt symptoms. 5. To rule out benign renal glycosuria
- 5. Contraindications of OGTT Established Or Confirmed Diabetic Patient No Role Of GTT In Follow Up Of Diabetes Mellitus Acutely ill Patients
- 6. The Patientis instructed to have good carbohydrate diet for 3 days prior to the test. Diet containing about 30-50gm of carbohydrate should be taken on the evening prior to the test. Patient should avoid drugs influencing glucose levels like hypglycemics, corticosteroids etc for at least 2 days prior. No Strenuous exercise on previous day. Patient should be on 12 hr fast 8PM to 8 AM next morning. NO TEA –COFFEE – BISCUITS etc . No smoking during the test Preparation of Patient for OGTT:-
- 7. PROCEDURE OF GTT Overnight Fasting (Min 8 Hrs ) A blood and urine sample is collected in the fasting state. Glucose Load :- Give 75g anhydrous glucose(flavoured if possible) in 250 – 300 ml water . ( Fixed Dose , For Children 1.75g/kg body weight). A full adult dose should not be given to a person weighing less than 43 kg (94 lb), or exaggerated glucoses may produce a false positive result. Ask To Drink Slowly –in 5 mins Flavouring Decreases Vomiting Sample Collection :- Fasting blood & urine sample is collected before giving glucose load. EVERY ½ HOURLY BLOOD AND URINE SAMPLE FOR NEXT 2 ½ HOURS (i.e Total 6 samples including fasting)
- 8. Decreased GlucoseTolerance: In Diabetes mellitus In hyperactivity of anterior pituitary & adrenal cortex In hyperthyroidism. Increased Glucose Tolerance: Hypopitutarism Hyperinsulinism Hypothyroidism Adrenal cortical hypofunction (such as Addison’s disease) In decreased absorption, like sprue, caeliac disease.
- 9. Fasting 1/2 hour1 hour 1 1/2 hour 2 hour 2 1/2 hour Blood Sugar 75 130 150 100 65 76 -10 10 30 50 70 90 110 130 150 170 190 Conc.BloodGlucose inmg/dl Normal GTT Urine Sugar nil nil nil nil nil nil
- 10. Fasting 1/2 hour1 hour 1 1/2 hour 2 hour 2 1/2 hour Blood Sugar 130 200 280 260 220 170 0 50 100 150 200 250 300 Conc.BloodGlucose inmg/dl Moderate Diabetic curve Urine Sugar nil ++ ++ ++ ++ nil
- 11. Fasting 1/2 hour1 hour 1 1/2 hour 2 hour 2 1/2 hour Blood Sugar 230 300 345 365 350 330 0 50 100 150 200 250 300 350 400 Conc.BloodGlucose inmg/dl Severe Diabetic curve Urine Sugar ++ +++ +++ ++++ +++ +++
- 12. Fasting 1/2 hour1 hour 1 1/2 hour 2 hour 2 1/2 hour Blood Sugar 90 130 139 110 90 85 0 20 40 60 80 100 120 140 160 180 200 Conc.BloodGlucose inmg/dl Renal Glycosuria Urine Sugar + or trace + + + + or trace + or trace
- 13. Fasting 1/2 hour1 hour 1 1/2 hour 2 hour 2 1/2 hour Bl. Sugar 80 220 190 110 80 65 0 30 60 90 120 150 180 210 240 Conc.BloodGlucose inmg/dl Lag curve Urine Sugar Nil ++ + Nil Nil Nil
- 14. 0 50 100 150 200 250 300 350 400 Fasting 1/2 hour1 hour 1 1/2 hour 2 hour 2 1/2 hour Normal GTT Moderate Diabetic curve Severe Diabetic curve
- 15. 0 30 60 90 120 150 180 210 240 Fasting 1/2 hour1 hour 1 1/2 hour 2 hour 2 1/2 hour Renal Glycosuria Lag curve
- 16. Fasting 1/2 Hr1 Hr 1 1/2 Hr 2 Hr 2 1/2 Hr Bl. Glucose 75 80 70 60 50 45 0 10 20 30 40 50 60 70 80 90BloodGlucosemgs/dl Urine Sugar Nil ++ + Nil Nil Nil
- 17. Fasting 1/2 Hour1 Hour 1 1/2 Hour 2 Hour 2 1/2 Hour Blood Glucose mgs/dl 75 80 70 60 50 45 0 10 20 30 40 50 60 70 80 90 BloodGlucosemgs/dl
- 18. 0 20 40 60 80 100 120 140 160 180 200 0 1 1.52 HOURS Renal glycosuria Alimentary Glycosuria URINE SUGAR RENAL GLYCOSURIA - + + + ALIMENTARY GLYCOSURIA - + - - P L A S M A G L U C O S E
- 19. Thank you Contactno. – 07418831766 E mail – Ashok Katta Dept. of Biochemistry, Dhanalakshmi Srinivasan Medical College, Perambalur