To investigate whether hyperglycemia in glucose-intolerant patients without diabetes could lead to increased nosocomial infections in the surgical intensive-care unit (ICU). A prospective, randomized, controlled clinical trial was conducted in the surgical ICU of a large teaching hospital in Hartford, Connecticut. Adult patients admitted to a 12-bed surgical ICU requiring treatment of hyperglycemia (glucose values > or = 140 mg/dL) were randomly assigned to receive standard insulin therapy (target glucose range, 180 to 220 mg/dL) or strict insulin therapy (target glucose range, 80 to 120 mg/dL) throughout their ICU stay. Demographic data, comorbidities, and confounding variables were analyzed. Outcome measures included mean daily serum glucose values, mean daily insulin doses, and number of nosocomial infections during the ICU stay. The study was completed by 61 critically ill surgical patients (27 in the standard glucose control group and 34 in the strict glucose control group). A significant reduction (P<0.001) in mean daily glucose level was achieved in the strict glycemic control group (125 +/- 36 mg/dL) in comparison with the standard glycemic control group (179 +/- 61 mg/dL). Furthermore, a significant reduction (P<0.05) in the incidence of total nosocomial infections, including intravascular device, bloodstream, intravascular device-related bloodstream, and surgical site infections, was observed in the strict glucose control group in comparison with the standard glucose control group. The incidence of hypoglycemia (glucose levels <60 mg/dL) was significantly increased (P<0.001) in the strict glycemic control group in comparison with the standard glycemic control group (32% versus 7.4% of patients or 0.8% versus 0.1% of total serum glucose values, respectively). Strict glycemic control is a safe and effective method for reducing the incidence of nosocomial infections in a predominantly nondiabetic, general surgical ICU patient population.