Introduction: It is accepted that preventing hyperglycaemia during critical illness while assuring adequate caloric intake can reduce mortality and morbidity. The aim of this study was to compare the metabolic effects of metformin and insulin on hyperglycaemia in ICU patients.
Methods: This double-blind randomised clinical trial was performed on 24 patients who were admitted to the intensive care unit (ICU) from 20 March to 20 September 2007. All patients with serious injuries or with major non-abdominal surgeries were included if they met the inclusion criteria, and were assigned randomly to one of the study groups. Patients in Group 1 received intensive insulin therapy, and patients in Group 2 were treated with metformin. Moreover, the Acute Physiology And Chronic Health Evaluation (APACHE) II scoring system was used to grade disease severity.
Results: Both glycaemic management protocols led to significantly improved glucose levels without any report of hypoglycaemia. The mean initial glucose levels for the insulin group decreased significantly after the intravenous infusion of insulin (p < 0.001). Additionally, the blood glucose concentration was significantly lower after two weeks of metformin administration compared to baseline measurements (p < 0.001). Moreover, the blood glucose concentration decrease during these two weeks was significantly higher in the insulin group (p = 0.01). Besides, APACHE II score was lower than baseline at the end of the study for both therapeutic groups (score of 10 vs. 15 [insulin] and 16 [metformin]). Finally, new renal dysfunction (maximum serum creatinine level at least double the initial value) was observed in three of the patients (two patients from the metformin group and one from the insulin group) in the last days of the protocol, although none of the patients showed lactic acidosis after ICU admission.
Conclusions: Both metformin and intensive insulin therapy significantly decreased hyperglycaemia in ICU patients. Insulin caused a greater reduction in blood glucose concentration but required more attention and trained personnel.