Comparative Study of Glucose and Fructose Metabolism in Infants with Reference to Utilization and to the Accumulation of Glycolytic Intermediates

Recently considerable interest has been directed at the comparative rates of utilization of glucose and fructose, administered intravenously. The present study was designed to carry out such a comparison using intakes of the carbohydrates which would provide sufficient calories to meet the maintenance requirements. The observations included a comparison of the extent of accumulation of certain acid metabolites and disturbances of the acid-base equilibrium which result from the rapid infusion of glucose and fructose. It was found that infusions of glucose and fructose in solution with electrolytes at 1 gm/kg/hr enabled both sugars to be utilized completely, without significant differences in the excretion of water, sodium and potassium. When the sugars were infused at a rate of 2 gm/kg/hr, 20% of the glucose and 9.9% of the fructose were excreted in the urine. Excretion of sodium in the urine with infusions of glucose led to loss of 79% of the intake, while for fructose the urinary excretion was 127% of intake, although no significant differences in excretion of water and potassium were noted. Infusions of fructose were accompanied by much greater increases of lactate and pyruvate in the blood than were caused by infusions of glucose. The urinary excretion of lactic acid was also greater with fructose than with glucose. It is stated that the superior utilization of fructose at rapid rates of infusion is not entirely advantageous because of the accompanying acidosis, which is of sufficient severity to make limitation of the rate of its infusion advisable.