Prevalence and prognostic value of hyperglycaemia

Acute hyperglycaemia has been associated with complications, prolonged intensive care unit and hospital stay, and increased mortality. We made an inventory of the prevalence and prognostic value of hyperglycaemia, and of the effects of glucose control in different groups of critically ill patients. The prevalence of hyperglycaemia in critically ill patients, using stringent criteria, approaches 100%. An unambiguous negative correlation between hyperglycaemia and mortality has been described in various groups of critically ill patients. Although the available evidence remains inconsistent, there appears to be a favourable effect of glucose regulation. This effect on morbidity and mortality depends on patient characteristics. To be able to compare results of future studies involving glucose regulation, better definitions of hyperglycaemia (and consequently of normoglycaemia) and patient populations are needed. Introduction Acute hyperglycaemia is frequently present in situations of stress, both in diabetic and in nondiabetic patients [1-3]. Because it is so common, it could be viewed as a physiologic adaptation during the ‘fight or flight’ response. On the other hand, it has been associated with complications, prolonged intensive care unit (ICU) and hospital stay, and increased mortality. The important issue is whether hyperglycaemia is just related to disease severity or is an independent risk factor that contributes to morbidity and mortality [4]. If hyperglycaemia is an independent risk factor, then tight glucose control (TGC) may have beneficial effects on morbidity and mortality. Conversely, if hyperglycaemia is not a risk factor per se, then the risks associated with glucose control may outweigh the benefits. We made an inventory of the prevalence and prognostic value of hyperglycaemia, and of the effects of glucose control in different groups of critically ill patients, in order to evaluate the available evidence. Prevalence and prognostic value of hyperglycaemia Table 1 provides an overview of various situations in which a correlation between hyperglycaemia and mortality has been demonstrated. Different authors use different threshold values to define hyperglycaemia. General hospital patients Among patients admitted to a general hospital, 38% exhibited increased blood glucose (BG) values, defined as either fasting BG values above 7 mmol/l or two random values above 11.1 mmol/l [5]. In that retrospective study 16% of 223 patients admitted with new onset hyperglycaemia (without a history of diabetes mellitus) died during their stay in hospital, as compared with only 1.7% of 1168 patients without hyperglycaemia (P < 0.001). The cause of death in the hyperglycaemia group was more often related to infection (33% versus 20% without hyperglycaemia) or acute neurological complications (19% versus 10%). Patients with new onset hyperglycaemia had a longer hospital stay and were more often admitted to the ICU (29% versus 9%). In this study, diabetic patients had a better prognosis than newly hyperglycaemic patients. Intensive care unit patients In one study conducted in medical ICU patients [6], admission BG was above 11.1 mmol/l in 23%. In another study [7], conducted in thoracosurgical ICU patients, admission glucose was above 6.1 mmol/l in 86% and almost Review Hyperglycaemia in critically ill patients: marker or mediator of mortality? Anouk M Corstjens1, Iwan CC van der Horst2, Jan G Zijlstra3, AB Johan Groeneveld4, Felix Zijlstra2, Jaap E Tulleken3 and Jack JM Ligtenberg3 1Department of Anaesthesiology, Intensive & Respiratory Care Unit, University Medical Center Groningen, Groningen, The Netherlands 2Department of Cardiology, University Medical Center Groningen, Groningen, The Netherlands 3Intensive & Respiratory Care Unit, University Medical Center Groningen, Groningen, The Netherlands 4Department of Intensive Care, Vrije Universiteit Medical Center, Amsterdam, The Netherlands Corresponding author: Jack JM Ligtenberg, [email protected] Published: 27 June 2006 Critical Care 2006, 10:216 (doi:10.1186/cc4957) This article is online at http://ccforum.com/content/10/3/216 © 2006 BioMed Central Ltd AMI = acute myocardial infarction; BG = blood glucose; CVA = cerebrovascular accident; GIK = glucose–insulin–potassium; ICU = intensive care unit; TGC = tight glucose control.