INTRODUCTION This paper deals with certain of the results of a study, begun in 1916, on the diagnosis of certain endocrine disorders. The compilation of the data has been greatly delayed, but within the last two years, however, it has been possible to prosecute the studies actively, and this report embodies a small completed portion of the whole investigation. In evaluating the mass of data resulting from earlier animal experimentation, it was felt that the greatest caution was imperative in translating it into terms of human experience. By confining the studies to man, one major cause of uncertainty has been eliminated. While this has imposed certain limitations, the direct applicability of the results has brought ample compensation. REASONS FOR SELECTION OF CARBOHYDRATE METABOLISM AS BASIS OF STUDY With the selection of the subjects for experiment, the natural sequel was the determination of the tests to be applied. The field of