Glycemic variability and outcome in critically ill

BACKGROUND: Acute hyperglycemia, hypoglycemia and glycemic variability (GV) have been found to be the three principal domains of glycemic control, which can adversely affect patient outcome. GV may be the confounding factor in tight glycemic control trials in surgical and medical patient. OBJECTIVE: This study was conducted to establish if there was any relationship between GV and intensive care unit (ICU) mortality in the Indian context. STUDY DESIGN: A retrospective review of a large cohort of prospectively collected database. SETTING: Adult Medical/Surgical/Trauma/Neuro ICU of a tertiary care hospital. PATIENT POPULATION: All patients who had four or more blood glucose measured during the ICU stay. OUTCOME: ICU mortality. RESULT: 2208 patients with a total of 11,335 blood glucose values were analyzed. GV measured by the standard deviation (SD) of mean blood glucose and glycemic lability index (GLI), both were significantly (P < 0.001) associated with ICU mortality. This relationship was maintained (odds ratio (OR): 2.023, 95% confidence interval (CI): 1.483-2.758) even after excluding patients with hypoglycemia (<60 mg/dl). Patients with blood glucose values in the euglycemic range but highest SD had higher mortality (54%) compared to mortality (24%) in patients above the euglycemic range. Similarly patients with blood sugar values below the average for study cohort and high GLI, another marker of GV had higher mortality (OR: 5.62, CI: 3.865-8.198) than compared to patients in the hyperglycemic range, reflecting the importance of GV as a prognostic marker in patients with blood sugar in the euglycemic range. CONCLUSION: This study demonstrated that high glucose variability is associated with increased ICU mortality in a large heterogeneous cohort of ICU patients. This effect was particularly evident among patients in the euglycemic range.