In 1979 and 1980, WHO and ADA (American Diabets Association) groups defined the diagnostic criteria for diabetes mellitus as well as other intermediate categories of blood glucose levels. Prior to this there were many classifications and ainbiguous terminologies, which are now obsolete.The Oral glucose tolerance test (OGTT) has been the gold standxd Tor the diagnosis of diabetes. However, in modern clinical practice, fasting and two hour post-prandiuL glucose values after a standard breakfast are acceptable, and thc OGTT is reserved f o r specific .situations terminologies of Performing an OGTT
The patient should have a normal unrestricted diet for three days consisting of 200 grams of carbohydrate. After an overnight fast of 10 hours, a blood sanlplc is taken.Thereafter 75 grams of glucose is administered in 250-300 ml of water. Afier two hours a blood sainple is collected for glucose. The test is interpreted according to t h e table below:
Note:If capillary blood is used (as in glucometer), then the postprandial values >220 mgs are diagnostic.If venous wl~ole blood is being used then each value of plasma glucose should be reduced by 15 per cent.Impaired Glucose Tolerance This is an intermediate class of glucose intolerance. The fasting values are within the normal levels but greater than 110 mgs; the two hour post-prandial levels are in between normal and diabetics (>I40 mgs but <200 mgs). The reason for identifying this group is because it has been shown that this group is as susceptible as diabetics to the macro-vascular complications, but not to the rnicrovasculal- complications. Also a small proportion of these people (about 3-5 per cent) g o on to develop frank diabetes mellitus in a few years. Hence it is important to detect and follow up these patients.
Impaired Fasting Glucose
This is another intermediate group of patients where the post prandial value is 4 4 0mgs, but the fasting value is in the range 110 to 125 mgs per cent).
Who Should be Screened for Diabetes?
Since diabetes is genetically determined a positive fanily history is a criterion for early screening for the disease. A person who has two diabetic parents has a 100 per cent chance of developilig diabetes soinetiine in hislher life, and has been te~med "prediabetes", though this is 1101 a popular term now. The risk of diabetes is high even if one parenl, or a close relative is diabetic, and all such patients should be tested even in the 31d to 4"' decade, and especially if the person is obese.
Diagnosis of Gestational Diabetes
Screening for Gestational Diabetes
At 24 to 28 weeks gestation, all pregnant wornen who have not been screened should have a 50 gms glucose load at ally Liiile of day (no need for fasting), and a one hour post glucose value >I40 mgs indicates need to do a OGTT as lollows.
Diagnosis of Gestatiolzal Diabetes Mellitus
Sullivan Criteria I OOgm OGTT
1)Administration of 100gms oral glucose at least 8 hours and no inore than 14 hours after a overnight fast and in the preceding 3 days should have had an unrestricted carbohydrate diet.
2) Plasma glucose is measured at fasting, I , 2 and 3 hours after glucose ingestion.
3) Inteipretation: Two or more o l the following plasma glucose values must be met or exceeded for a positive diagnosis:
Fasting 105 mgs.
1 hour 190 mgs.
2 hours 165 mgs.
3 hours 145 mgs.
11) WHO Criteria
This uses a 75 gms. glucose load and checks plasma glucose at two hour post glucose.A value of >I40 mgs per cent is diagnostic of GDM.There are several other criteria and there is considerable ongoing reseuch to define the exacl threshold level of glucose intolerance at which the health of the mother and foetus and subsequent life of tlie offspring are in danger of diabetes induced hazards
The patient should have a normal unrestricted diet for three days consisting of 200 grams of carbohydrate. After an overnight fast of 10 hours, a blood sanlplc is taken.Thereafter 75 grams of glucose is administered in 250-300 ml of water. Afier two hours a blood sainple is collected for glucose. The test is interpreted according to t h e table below:
Note:If capillary blood is used (as in glucometer), then the postprandial values >220 mgs are diagnostic.If venous wl~ole blood is being used then each value of plasma glucose should be reduced by 15 per cent.Impaired Glucose Tolerance This is an intermediate class of glucose intolerance. The fasting values are within the normal levels but greater than 110 mgs; the two hour post-prandial levels are in between normal and diabetics (>I40 mgs but <200 mgs). The reason for identifying this group is because it has been shown that this group is as susceptible as diabetics to the macro-vascular complications, but not to the rnicrovasculal- complications. Also a small proportion of these people (about 3-5 per cent) g o on to develop frank diabetes mellitus in a few years. Hence it is important to detect and follow up these patients.
Impaired Fasting Glucose
This is another intermediate group of patients where the post prandial value is 4 4 0mgs, but the fasting value is in the range 110 to 125 mgs per cent).
Who Should be Screened for Diabetes?
Since diabetes is genetically determined a positive fanily history is a criterion for early screening for the disease. A person who has two diabetic parents has a 100 per cent chance of developilig diabetes soinetiine in hislher life, and has been te~med "prediabetes", though this is 1101 a popular term now. The risk of diabetes is high even if one parenl, or a close relative is diabetic, and all such patients should be tested even in the 31d to 4"' decade, and especially if the person is obese.
Diagnosis of Gestational Diabetes
Screening for Gestational Diabetes
At 24 to 28 weeks gestation, all pregnant wornen who have not been screened should have a 50 gms glucose load at ally Liiile of day (no need for fasting), and a one hour post glucose value >I40 mgs indicates need to do a OGTT as lollows.
Diagnosis of Gestatiolzal Diabetes Mellitus
Sullivan Criteria I OOgm OGTT
1)Administration of 100gms oral glucose at least 8 hours and no inore than 14 hours after a overnight fast and in the preceding 3 days should have had an unrestricted carbohydrate diet.
2) Plasma glucose is measured at fasting, I , 2 and 3 hours after glucose ingestion.
3) Inteipretation: Two or more o l the following plasma glucose values must be met or exceeded for a positive diagnosis:
Fasting 105 mgs.
1 hour 190 mgs.
2 hours 165 mgs.
3 hours 145 mgs.
11) WHO Criteria
This uses a 75 gms. glucose load and checks plasma glucose at two hour post glucose.A value of >I40 mgs per cent is diagnostic of GDM.There are several other criteria and there is considerable ongoing reseuch to define the exacl threshold level of glucose intolerance at which the health of the mother and foetus and subsequent life of tlie offspring are in danger of diabetes induced hazards
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