Glucose Turnover, Oxidation, and Indices of Recycling in Severely Traumatized Patients

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Abstract
Hyperglycemia is often seen in trauma patients and its etiology is not clearly understood. We have determined parameters of glucose metabolism by using simultaneous primed-constant intravenous infusion of both [6-3H] glucose and [U-14C] glucose in ten severely traumatized hypermetabolic subjects during the early "flow phase'' of injury and in six post-absorptive normal volunteers. The mean rate of glucose production (determined by means of [6-3H] glucose) was 3.96 .+-. 0.40 mg/kg/min in trauma patients, which was significantly (p = 0.025) higher than the value of 2.75 .+-. 0.13 observed in normal volunteers. Glucose turnover rates determined with [U-14C] glucose as tracer were lower in all subjects. The difference between the turnover rates determined by the two tracers represents an index of recycling of glucose through three-carbon fragments. This recycling index was similar in both groups of subjects in amount (0.24 .+-. 0.07 vs. 0.26 .+-. 0.08 mg glucose/kg/min) but different when expressed as percentage of total glucose turnover (5.6 .+-. 1.4% vs. 9.8 .+-. 1.7%; p = 0.05). Thje absolute rates of glucose clearance, oxidation, and recycling were similar in stress trauma patients and unstressed controls although the rate of production was increased by 44% due to injury. Post-trauma hyperglycemia was mainly due to an increased hepatic output of glucose and not due to a decreased ability of the tissue to extract glucose from the plasma. Hyperglycemia may be the driving force in the metabolic effects of injury.