There are four cardinal points in the diagnosis of this interesting anomaly: (a) a glycosuria without hyperglycemia; (b) little, if any, relationship between the carbohydrate intake and the amount of glucose excreted in the urine; (c) the absence of the signs and symptoms characteristic of diabetes mellitus, and (d) a long period of observation during which the patient shows no tendency to develop diabetes mellitus. Joslin1 lays particular stress on the last criterion, which is the most difficult to carry out. A critical review of the literature is made by Goto,2 Bailey,3 Strouse4 and Lewis and Mosenthal.5 When preparing data connected with the report in 1915, Lewis and Mosenthal found less than ten cases which were described in sufficient detail to warrant their acceptance as instances of true renal glycosuria, but since that time at least nine other cases6 have been noted. With the more careful observations of the blood