Why is a glucose tolerance test done with 75 grams of glucose and not another quantity?

The American Diabetes Association recommends a standard oral glucose tolerance test for adults of 75 grams of glucose in 250 to 300 milliliters of water. The purpose of this uniformity is to help to standardize the limits between normal and impaired glucose tolerance and between the latter and overt diabetes and to provide a uniform basis for comparing control and test subjects in clinical trials..

There will be some adults though for whom this definition is inappropriate, and of course that is true also for children. For this reason, some laboratories use a variable dose of 42 grams per meter square of body surface area as the loading dose as well as other standards in the case of children, where this test has been largely supplanted by the Intravenous glucose tolerance test (IVGTT).

DOB