Research

The impact of early hypoglycemia and blood glucose variability on outcome in critical illness

Sean M Bagshaw^1,2 , Rinaldo Bellomo^2,3 , Michael J Jacka^1,4 , Moritoki Egi⁵ , Graeme K Hart^2,3 and Carol George⁶ for the ANZICS CORE Management Committee

¹Division of Critical Care Medicine, University of Alberta Hospital, University of Alberta, 8440-112 ST NW, Edmonton, Alberta, Canada, T6G2B7

²Department of Epidemiology and Preventive Medicine, Monash University, Alfred Hospital, Melbourne, Victoria 3004, Australia

³Faculty of Medicine, University of Melbourne, 766 Elizabeth Street, Melbourne, Victoria 3010, Australia

⁴Department of Anesthesiology and Pain Medicine, University of Alberta Hospital, University of Alberta, 8440-112 ST NW, Edmonton, Alberta, T6G 2B7 Canada

⁵Department of Anesthesiology and Resuscitology, Okayama University Hospital, 2-5-1 Shikata-cho, Okayama, 700-8558 Japan

⁶Australia New Zealand Intensive Care Society (ANZICS) Adult Patient Database (APD), 10 Ievers Terrace, Carlton, Victoria 3053, Australia

author email corresponding author email

Critical Care 2009, 13:R91doi:10.1186/cc7921

Published:	17 June 2009

Abstract

Introduction

In critical illness, the association of hypoglycemia, blood glucose (BG) variability and outcome are not well understood. We describe the incidence, clinical factors and outcomes associated with an early hypoglycemia and BG variability in critically ill patients.

Methods

Retrospective interrogation of prospectively collected data from the Australia New Zealand Intensive Care Society Adult Patient Database on 66184 adult admissions to 24 intensive care units (ICUs) from 1 January 2000 to 31 December 2005. Primary exposure was hypoglycemia (BG < 4.5 mmol/L) and BG variability (BG < 4.5 and ≥ 12.0 mmol/L) within 24 hours of admission. Primary outcome was all-cause mortality.

Results

The cumulative incidence of hypoglycemia and BG variability were 13.8% (95% confidence interval (CI) = 13.5 to 14.0; n = 9122) and 2.9% (95%CI = 2.8 to 3.0, n = 1913), respectively. Several clinical factors were associated with both hypoglycemia and BG variability including: co-morbid disease (P < 0.001), non-elective admissions (P < 0.001), higher illness severity (P < 0.001), and primary septic diagnosis (P < 0.001). Hypoglycemia was associated with greater odds of adjusted ICU (odds ratio (OR) = 1.41, 95% CI = 1.31 to 1.54) and hospital death (OR = 1.36, 95% CI = 1.27 to 1.46). Hypoglycemia severity was associated with 'dose-response' increases in mortality. BG variability was associated with greater odds of adjusted ICU (1.5, 95% CI = 1.4 to 1.6) and hospital (1.4, 95% CI = 1.3 to 1.5) mortality, when compared with either hypoglycemia only or neither.

Conclusions

In critically ill patients, both early hypoglycemia and early variability in BG are relatively common, and independently portend an increased risk for mortality.