Effect of furosemide administration on glucose tolerance, insulin-and HGH response following parenteral glucose loading was studied in healthy subjects. Effects of potassium or calcium on the furosemide induced changes were also observed in the same subjects. Furosemide administration resulted in a considerable reduction in the magnitude and duration of insulin response although no obvious changes were observed in glucose disappearance from the circulation. Oral potassium or calcium supplement to the furosemide treated subjects showed a reversion toward normal of the insulin response. The author suggested that a decreased endogenous insulin production resulting from the potassium and/or calcium depletion is responsible for the changes observed. In those subjects who receive parenteral nutrition if administration of furosemide is essential, it should be supplemented by potassium and/or calcium.