Parenteral Glucose and Glucose Control in the Critically Ill: A Kinetic Appraisal

Abstract

Background: We investigated the influence of parenteral glucose infusion on insulin-driven tight glucose control (4.4–6.1 mmol/liter) in the critically ill by appraising kinetic characteristics of the glucoregulatory system. Methods: Turnover characteristics of the glucoregulatory system associated with constant 0, 1.2, and 2.4 mg/kg/min parenteral glucose infusion were obtained by literature review and mass-balance calculations. Results: Without parenteral glucose infusion, the achievement of tight glucose control is hampered by long time delays with an anticipated glucose equilibration half-time ( T1/2) of 185 min. The constant parenteral glucose infusions of 1.2 and 2.4 mg/kg/min reduce T1/2 to 80 and 40 min, respectively. This follows on from the accelerated glucose turnover brought about by the insulin-modulated glucose uptake, which increases in response to increasing exogenous insulin required to achieve tight glucose control. However, large variations exist among glucose turnover characteristics in the critically ill. Conclusions: The constant parenteral glucose infusion greater or equal to 2.4 mg/kg/min is expected to simplify the achievement of tight glucose control by reducing system delays and may facilitate the development of more intuitive, efficacious, and safer insulin-titration guidelines.