The clinical course of diabetes mellitus may be characterized by extreme lability. In some patients the mechanism responsible for this lability is unknown, but in other cases the "brittle" diabetes is associated with excess insulin administration,1-4 pregnancy,5 or hyperthyroidism.6That pre-existing diabetes mellitus may be made labile by the development of renal glycosuria has not been reported previously. Four such patients are described in this report.
Materials and Methods
Four young diabetic males were found to have renal glycosuria during hospitalization at the University of Utah Affiliated Hospitals from 1957 to 1961 by means of simultaneous blood and urine glucose determinations made on several occasions in each case as follows: The patient was asked to empty the bladder. Thirty minutes later he again voided, and a venous blood sample was obtained. The glucose concentration in the 30-minute urine sample was compared to the glucose level in