Parenteral glucose and glucose control in the critically ill: a kinetic appraisal

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.

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.

Without parenteral glucose infusion, the achievement of tight glucose control is hampered by long time delays with an anticipated glucose equilibration half-time (T((1/2))) of 185 min. The constant parenteral glucose infusions of 1.2 and 2.4 mg/kg/min reduce T((1/2)) 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.

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.