Characterization of persistent hyperglycemia: what does it mean postinjury?

BACKGROUND: Strict glycemic control has been shown to reduce both morbidity and mortality in critically ill surgical patients; however, overly aggressive management of hyperglycemia may also be associated with deleterious effects. We sought to characterize clinical outcomes associated with different levels of persistent hyperglycemia (PH) in a cohort of severely injured patients with trauma, when a strict glycemic control protocol (target glucose 80-110 mg/dL) was implemented.
METHODS: Data were obtained from a multicenter prospective cohort study evaluating clinical outcomes in blunt injured adults with hemorrhagic shock. Glycemic control was analyzed using the average maximum daily glucose values from postinjury day 2 (>48 hours after injury) to postinjury day 5. PH was defined as a mean glucose value >130 mg/dL, and was categorized into three different severity levels (I-III) based on the distribution of mean 4-day glucose values for the cohort. Separate Cox proportional hazard regression models were then used to determine whether PH was independently associated with mortality and nosocomial infection (NI), and the level of glycemic control that was associated with these poor outcomes.
RESULTS: Overall mortality and NI rates for the study population (n = 862) were 10.8% and 49.6%, respectively. Cox proportional hazard regression revealed that PH was independently associated with almost an 80% higher mortality in patients with mean 4-day glucose values >145 mg/dL (group II) and almost a twofold higher mortality in patients with >165 mg/dL (group III). However, PH was not independently associated with a higher risk of NI at any level. Patients with PH did have a higher incidence of early multiple organ failure (within first 48 hours: 30.2% vs. 41.6% p = 0.001), which preceded the documentation of PH in the majority of patients.
CONCLUSION: Maintenance of daily maximum glucose values <145 mg/dL was independently associated with a survival benefit after injury. Patients with PH, despite aggressive insulin therapy, had a higher incidence of multiple organ failure and an associated higher risk of mortality. However, the strict glycemic control protocol in the current trauma cohort seems to have prevented the association of PH and infectious complications, which has been documented in prior studies. This analysis further validates the importance of strict glycemic control after injury, and highlights the need for further studies on the mechanism responsible for these findings.