The Glucose Tolerance Test

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A recent increase in the number of standard oral glucose tolerance tests done in our laboratory prompted an investigation of the validity of the generally accepted criteria for the interpretation of these studies. The results of all glucose tolerance tests performed in this laboratory during a representative 12-week period were categorized and tabulated. With glucose tolerance tests, as with most laboratory studies, the most meaningful interpretation rests on correlation with clinical findings. This study, however, concerns analysis solely of laboratory results.


The glucose tolerance test, for the purpose of this study, is defined as the determination of the blood sugar level at a specified interval or intervals after administration of a standardized amount of glucose. Results of tests that included two or more blood sugar determinations were considered tolerance curves. The results of all the glucose tolerance tests performed in our laboratory from April 8, 1963, through June 28, 1963, were reviewed. Glucose tolerance tests were administered to 630 patients at the Cleveland Clinic during this 12-week period, an average of 52.5 such studies each week. The results of each individual test were interpreted as normal, abnormal, or equivocal. These categories were based on the ranges of normal established for our laboratory, and were modified in some instances by consideration of the patient’s overall response.

Blood sugar levels were determined on venous blood samples by an automated procedure, using the potassium ferricyanide — potassium ferrocyanide oxidation reduction method1 as modified2,3 for use on the AutoAnalyzer. The glucose administered to the. . .



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