Glycosuria is of clinical significance. The development of diabetes in young adults is slow and resolves itself into 4 stages, respectively: diminished tolerance; diminished tolerance and assimilation; chemical diabetes; clinical diabetes. Excellent results may be accomplished by diet alone, and there may be a return to normal tolerance if therapy is instituted in patients of Groups III and IV. In early clinical diabetes results are satisfactory, but if the condition progresses and severe symptoms occur, good results become more difficult to attain. In this age group, the presence of obesity or a family history of diabetes was not significant in enabling one to predict which of 2 individuals with disturbed glucose tolerance would ultimately develop diabetes. Loss of wt. alone is not responsible for improvement in tolerance. The renal threshold for glucose is not stationary. It would appear that after recovery the individual must continue to restrict his diet and maintain a normal or subnormal wt. to be able to retain a normal carbohydrate metabolism. Diabetes may not be wholly due to a lack of insulin but rather to a failure in utilization of insulin by the body.