Glucose Tolerance Tests

Figure 19-6. Glucose tolerance test. Blood glucose curves of a normal and a diabetic individual after oral administration of 50 g of glucose. Note the initial raised concentration in the diabetic. A criterion of normality is the return of the curve to the initial value within 2 hours.

Patients may have CFRD, as indicated by blood glucose greater than or equal to 200 mg/dL (greater than or equal to 11.1 mmol/L) 2 hours after an oral glucose tolerance test. 

All women should be screened with an oral glucose tolerance test between weeks 24 and 28 of gestation unless they are in the low-risk category. 

Note In the absence of unequivocal hyperglycemia, these criteria should be confirmed by repeat testing on a different day. The oral glucose tolerance test is not recommended for routine clinical use. 

Diabetes mellitus3 2-Hour Postload Plasma Glucose (Oral glucose tolerance test) Greater than or equal to 126 7.0... 

GH level greater than 1 ng/mL (1 mcg/L) following an oral glucose tolerance test (OGTT) and elevated IGF-I level compared with age- and sex-matched control values. 

Electrolytes and renal function are within normal limits. Fasting blood glucose level is 206 mg/dL (11.43 mmol/L), HbA1c is 8.5%, and (-) microalbumin. GH level following an oral glucose tolerance test is 8 ng/mL (8 mcg/L). Elevated IGF-I at 790 ng/mL (790 mcg/L)... 

Glucose tolerance testing Fasting blood glucose, HbAlc if... 

MCV Mean corpuscular volume OGT Oral glucose tolerance test... 

Impaired glucose tolerance is diagnosed when the 2-hour postload sample of the oral glucose tolerance test is between 140 and 199 mg per dL (7.8 to 11.0 mmol/L). 

Uses of Specific Laboratory Tests to Discover, Confirm, and/or Exclude a Disease. Some tests can confirm the diagnosis of a disease (e.g., tissue histology from a broncho scopic biopsy to confirm lung cancer), but cannot be used to exclude the disease or discover the disease in routine screening. Other tests can be used both to confirm and to exclude the diagnosis of a disease (e.g., glucose tolerance test for diabetes mellitus), but are too inconvenient to be used to discover the disease in routine screening. The uses of each laboratory test to discover, confirm, or exclude a disease should be considered before a test is simply added to a clinical trial protocol. This ensures that the test is appropriate in the context of the planned clinical trial. 

In 2000, Merck in-licensed threo (3, P32/98) and alio (4) isoleucine thiazolidides from Probiodrug so as to fast forward the internal program and increase our understanding of DPP-4 inhibition. These two compounds are equipotent against DPP-4 (IC5o = 440 nM for 3 and 460 nM for 4), and each compound showed similar in vivo efficacies in oral glucose tolerance tests (OGTT) administered to diet-induced... 

Kar A, Choudhary BK, Bandhopadhyay NG. (1999) Preliminary studies on the inorganic constituents of some indigenous hypoglycaemic herbs on oral glucose tolerance test J Ethnopharm 64 179-184. 

Glucose Increases in blood glucose and alterations in glucose tolerance tests (fasting and 2 hour postprandial sugar) have been observed. 

Diabetes mellitus A /o d use of amiloride in diabetic patients. If it is used, monitor serum electrolytes and renal function frequently. Discontinue use 3 days or more before glucose tolerance testing. 

The diagnosis may be supported by an abnormal glucose tolerance test. 

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