Renal Glycosuria With a False-Positive Glucose Tolerance Test

RENAL GLYCOSURIA is usually differentiated from diabetes mellitus by the presence of an abnormal glucose tolerance test in the latter condition. For many years it has been standard procedure that a patient should receive a diet containing at least 200 to 250 gm of carbohydrates daily for three days prior to a glucose tolerance test since carbohydrate restriction in itself has been shown to impair the use of glucose.¹ It would seem reasonable that some persons with renal glycosuria, who had considerable glucose loss in their urine, might have insufficient amounts of carbohydrates available for use despite a normal carbohydrate intake. The lack of sufficient usable carbohydrate, prior to the test, might lead to a false-positive glucose tolerance test in a person with renal glycosuria. The following case report seems to be an example of this phenomenon.

Report of a Case  The patient, a 19-year-old man, was admitted to