Glycemic control improves outcome in cardiac surgical patients and after myocardial infarction or stroke. Hyperglycemic predicts poor outcome in trauma, but currently no data exist on the effect of glycemic control in critically ill trauma patients. In our intensive care unit (ICU), we use a subcutaneous sliding scale insulin protocol to achieve glucose levels <140 mg/dL. We hypothesized that aggressive glycemic control would be associated with improved outcome in critically ill trauma patients. At our urban Level 1 trauma center, a retrospective study was conducted of all injured patients admitted to the surgical ICU >48 hours during a 6-month period. Data were collected for mechanism of injury, age, diabetic history, Injury Severity Score (ISS), and APACHE II score. All blood glucose levels, by laboratory serum measurement or by point-of-care finger stick, were collected for the entire ICU stay. Outcome data (mortality, ICU and hospital length of stay, ventilator days, and complications) were collected and analyzed. Patients were stratified by their preinjury diabetic history and their level of glucose control (controlled <140 mg/dL vs non-controlled > or =141 mg/dL) and these groups were compared. During the study period, 103 trauma patients were admitted to the surgical ICU >48 hours. Ninety (87.4%) were nondiabetic. Most (83.5%) sustained blunt trauma. The average age was 50 +/- 21 years, the average ISS was 22 +/- 12, and the average APACHE II was 16 +/- 9. The average glucose for the population was 128 +/-25 mg/dL. Glycemic control was not attained in 27 (26.2%) patients; 19 (70.4%) of these were nondiabetic. There were no differences in ISS or APACHE II for controlled versus non-controlled patients. However, non-controlled patients were older. Mortality was 9.09 per cent for the controlled group and was 22.22 per cent for the non-controlled group. Diabetic patients were older and less severely injured than nondiabetics. For nondiabetic patients, mortality was 9.86 per cent in controlled patients and 31.58 per cent in non-controlled patients (P < 0.05). Also, urinary tract infections were more prevalent and complication rates overall were higher in nondiabetic patients with noncontrolled glucose levels. Nonsurvivors had higher average glucose than survivors (P < 0.03). Poor glycemic control is associated with increased morbidity and mortality in critically ill trauma patients; this is more pronounced in nondiabetic patients. Age may be a factor in these findings. Subcutaneous sliding scale insulin alone may be inadequate to maintain glycemic control in older critically ill injured patients and in patients with greater physiologic insult. Prospective assessment is needed to further clarify the benefits of aggressive glycemic control, to assess the optimal mode of insulin delivery, and to better define therapeutic goals in critically ill, injured patients.