Metabolic inefficacy of a short-term low-dose insulin regimen in critically ill patients: a randomized, placebo-controlled trial.

Objective: Hyperglycemia and protein catabolism frequently occur in critically ill patients and both are associated with increased complication rates. These metabolic alterations can be improved by insulin administered exogenously. Since a wide range of insulin dosages have been used, this randomized, placebo-controlled, investigator-blinded, clinical study tests the hypothesis that a low-dose insulin regimen improves hyperglycemia and protein catabolism in critically ill medical patients.

Patients And Methods: The day after their admission to a medical intensive care unit, forty consecutive, critically ill medical patients were randomized for receiving either a low-dose insulin regimen (i.e. 1 IU/h) (treatment group, n = 20) or placebo (control group, n = 20) continuously over 24 hours. The primary endpoint was the efficacy of the low-dose insulin regimen to decrease serum glucose concentrations; the secondary endpoint was its influence on protein catabolism. Serum glucose concentrations and protein catabolism, which was assessed by the urea nitrogen appearance rate, were determined at baseline and at 8 and 24 hours thereafter. Serum insulin concentrations were measured at baseline and after 24 hours.

Results: After 24 hours the low-dose insulin regimen increased serum insulin concentrations compared with baseline (16.8+/-13.3 microU/ml and 11.5+/-16.9 microU/ml, respectively; p<0.05). Hyperglycemia and the urea nitrogen appearance rate did not change within the two groups of patients and there was no difference between the groups at the different time points.

Conclusions: Administration of the low-dose insulin regimen was safe. However, the short-term low-dose insulin regimen was inefficient in influencing mild hyperglycemia and protein catabolism in critically ill medical patients.