Glucose tolerance test - OGTT Detai\\

1. Glucose
Tolerance
Test
(GTT)
A s h o k K a t t a

2. What is Glucose Tolerance Test?

3.  Glucose Tolerance
Glucose Tolerance 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 patient with 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 Patient is 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 Glucose Tolerance:
 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 hour 1 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 hour 1 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 hour 1 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 hour 1 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 hour 1 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 hour 1 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 hour 1 hour 1 1/2 hour 2 hour 2 1/2 hour
Renal Glycosuria Lag curve

16. Fasting 1/2 Hr 1 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 Hour 1 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 1.5 2 HOURS
Renal
glycosuria
Alimentary
Glycosuria
URINE SUGAR
RENAL GLYCOSURIA - + + +
ALIMENTARY GLYCOSURIA - + - -
P
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19. Thank you Contact no. – 07418831766
E mail –
Ashok Katta
Dept. of Biochemistry,
Dhanalakshmi Srinivasan Medical College,
Perambalur