In a previous study1 it has been shown that it is possible to change materially a subject's tolerance for dextrose by the use of different types of diet. The different types of diet used to demonstrate this effect were: one consisting strictly of protein, one of fats, one of carbohydrates; in another group food was not taken. The subjects of this experiment were normal, healthy, male medical students. They were instructed to follow certain of the dietary outlines mentioned for two days, and on the third morning, on a fasting stomach, a dextrose tolerance test was run on each subject with the use of 1.75 Gm. of dextrose per kilogram of body weight. Briefly, the results were: the subjects who had consumed only carbohydrates possessed a markedly increased tolerance for dextrose; those who had eaten only proteins showed a mild inability to remove the dextrose from the blood stream; whereas