Abstract
Various objections may be made to methods now in vogue for sugar tolerance determinations which depend on the appearance of sugar in the urine. Much more reliable, instructive and delicate results can be obtained by a study of the hyperglycemic response of the blood to ingested sugar. When pure glucose is administered in amounts equal to 13/4 gm. per kgm. body weight in 40 per cent. aqueous solution to fasting patients, alimental absorption is so regular that a normal hyperglycemic curve can be established. The blood sugar reattains its fasting level 11/2 to 2 hours after the sugar is taken. The oral method of administration is therefore much more certain than has been supposed.
For clinical purposes the test is carried out by first determining by Epstein's modification of the Lewis and Benedict method, the blood sugar of a patient who has fasted over night, then administering the sugar drink as prepared above, with the addition of the juice of a lemon and again determining the blood sugar at the end of two hours. In normal subjects the blood sugar has by this time returned to its fasting level. If hyperglycemia still persists, the blood sugar tolerance is lowered. This is the simplest form to which the technique is reducible. We prefer to make several half hourly or hourly observations of the blood sugar following glucose ingestion also to determine the presence and amount of sugar voided in the urine during these determinations and in the complete twen ty-four- hour specimen.
Glycosuria, which is normally absent under the conditions of the test, is not a necessary accompaniment of decreased tolerance. A normal blood sugar curve accompanied by glycosuria usually indicates renal diabetes. Mie have also found this test useful in the diagnosis of incipient diabetes.
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