Objective: The role of intensive insulin therapy in medical surgical intensive care patients remains unclear. The objective of this study was to examine the effect of intensive insulin therapy on mortality in medical surgical intensive care unit patients.

Design: Randomized controlled trial.

Settings: Tertiary care intensive care unit.

Patients: Medical surgical intensive care unit patients with admission blood glucose of > 6.1 mmol/L or 110 mg/dL.

Intervention: A total of 523 patients were randomly assigned to receive intensive insulin therapy (target blood glucose 4.4-6.1 mmol/L or 80-110 mg/dL) or conventional insulin therapy (target blood glucose 10-11.1 mmol/L or 180-200 mg/dL).

Measurements and main outcomes: The primary end point was intensive care unit mortality. Secondary end points included hospital mortality, intensive care unit and hospital length of stay, mechanical ventilation duration, the need for renal replacement therapy and packed red blood cells transfusion, and the rates of intensive care unit acquired infections as well as the rate of hypoglycemia (defined as blood glucose < or = 2.2 mmol/L or 40 mg/dL). There was no significant difference in intensive care unit mortality between the intensive insulin therapy and conventional insulin therapy groups (13.5% vs. 17.1%, p = 0.30). After adjustment for baseline characteristics, intensive insulin therapy was not associated with mortality difference (adjusted hazard ratio 1.09, 95% confidence interval 0.70-1.72). Hypoglycemia occurred more frequently with intensive insulin therapy (28.6% vs. 3.1% of patients; p < 0.0001 or 6.8/100 treatment days vs. 0.4/100 treatment days; p < 0.0001). There was no difference between the intensive insulin therapy and conventional insulin therapy in any of the other secondary end points.

Conclusions: Intensive insulin therapy was not associated with improved survival among medical surgical intensive care unit patients and was associated with increased occurrence of hypoglycemia. Based on these results, we do not advocate universal application of intensive insulin therapy in intensive care unit patients.

Trial registration: Current Controlled Trials registry (ISRCTN07413772) http://www.controlled-trials.com/ISRCTN07413772/07413772; 2005.