Glycated hemoglobin at admission in the intensive care unit: clinical implications and prognostic relevance

Objective This study investigated the clinical significance of HbA1c levels on admission in the intensive care unit (ICU) as a prognostic marker for morbidity and mortality in critically ill patients. Patients—methods This prospective observational study included consecutive patients admitted in an 8-bed multidisciplinary ICU. Patients were prospectively followed from ICU admission until ICU outcome (death/discharge). All patients had an HbA1c measurement upon admission in the ICU. Results Five hundred fifty-five consecutive patients (376 males, 179 females) were included in the study. In patients without prior diabetes mellitus (DM) diagnosis, a cutoff of 6.5% for HbA1c (diagnostic cutoff for DM) predicted more severe disease (as described by Acute Physiology and Chronic Health Evaluation II and Sequential Organ Failure Assessment scores at admission) and higher ICU mortality (adjusted odds ratio, 2.33; 95% confidence interval, 1.04 - 5.25). In the subgroup of patients with a history of DM, a cutoff of 7% for HbA1c (glycemic target) had no predicting ability for ICU mortality. Conclusions HbA1c is a useful tool for the diagnosis of a previously undiagnosed DM. This study showed that in critically ill patients with previously undiagnosed DM, HbA1c at admission is significantly associated with ICU mortality.