Utilization of intravenous glucose and fructose in the postoperative period

A comparison is made between the utilization of glucose and fructose given intravenously at the rates of 1 g kg-1 h-1 and 0.5 kg-1 h-1 to 6 and 10 patients, respectively, who had undergone stomach surgery. Each patient served as his own control. The maximum rise in the total blood sugar concentration during both the rapid and the slow glucose infusions (227 mg% and 171 mg%) was significantly larger than during the fructose infusions (86 mg% and 52 mg%). The maximum rise in blood glucose of an average 23 and 18 mg% during the administration of fructose seems to indicate that only a small percentage of fructose is converted directly to glucose. Hypoglycemia after the infusions was most pronounced after the use of glucose. During the rapid infusions the patients lost a significantly larger amount of the infused sugar in the urine when glucose was administered (12.9% vs 4.7%), and the greater loss of sugar was accompanied by a greater loss of water. During the slow infusions there was no difference in sugar excretion between the two carbohydrates. At the infusion rate of 0.5 g kg-1 h-1 6 times as much lactate was excreted during the fructose infusions as during the glucose infusions (1.8 mg as compared with 0.3 mg lactate kg-1 infusion h-1). The study seems to indicate that there is a renal threshold for lactate at blood concentrations of 10-15 mg%.