Severe hypoglycemia during intensive insulin therapy

Tight glycemic control reduces mortality in surgical intensive care patients and in long-term medical intensive care patients. A large study on intensive insulin therapy was prematurely discontinued due to safety issues. As the safety of intensive insulin therapy has been questioned, we screened all patients during a 17-month period to reveal the incidence of hypoglycemia and its effects on the outcome of the patients. All patients treated between February 2005 and June 2006 in two intensive care units (ICUs) of a tertiary care teaching hospital were included in the study. A nurse-driven intensive insulin therapy with a target blood glucose level of 4-6 mmol/l had been introduced earlier. The patients were divided into two groups according to the presence of severe hypoglycemia (<= 2.2 mmol/l). One thousand two hundred and twenty-four patients (1124 treatment periods) were included. During the study period, 61,203 blood glucose measurements were performed, 2.6% of which were below and 52.6% above the target range. Severe hypoglycemia (glucose <= 2.2 mmol/l) occurred in 25 patients (36 measurements). The incidence was 0.06% of the measurements and 2.3% of the patients. The median age, sex, Acute Physiology And Chronic Health Evaluation II, Simplified Acute Physiology Score II, diagnosis category, ICU or hospital length of stay did not differ between the groups. The hospital mortalities were 25% and 15% in patients with or without severe hypoglycemia, respectively (P=0.16). Severe hypoglycemia during intensive insulin therapy is rare in clinical practice compared with previous clinical trials.