Tight glycemic control increases the incidence of hypoglycemia in intensive care unit patients

Introduction

Hyperglycemia is common in critically ill patients. Tight glycemic control (aimed at blood glucose levels of 4.4–6.1 mmol/l) improved the mortality and morbidity in postoperative intensive care patients [1]. Tight glycemic control, however, bares the risk of hypoglycemia. The present study was performed to investigate whether the introduction of a nurse-driven tight glycemic control protocol in two general ICUs increases the incidence of (severe) hypoglycemia.

Methods

All measured plasma glucose levels in all patients admitted to a 28-bed academic ICU and to a 10-bed ICU of an affiliated teaching hospital from 1999 to 2003 were retrospectively collected from the hospital information systems. Severe hypoglycemia was defined as blood glucose levels < 2.2 mmol/l, and hypoglycemia as blood glucose levels < 4.4 mmol/l. Comparisons were made between the period before (1999–2001) and after (2002–2003) implementation of tight glycemic control. Directly after analysis of the aforementioned study results, an adjusted tight glucose protocol was implemented in daily ICU practice at the end of 2001.

Statistics

Data are means ± standard deviation. Comparisons between years were made by chi-square test. Statistical significance was accepted for P < 0.05.

Results

For all years, > 99% of data were retrieved in both centres. In the AMC approximately 220,000 blood glucose levels were collected (1999–2002: 3869 patients, 2002–2003: 2613 patients); in the GH approximately 35,000 blood glucose levels were collected (1999–2001: 1639 patients, 2002–2003: 1098 patients).

Conclusions

Tight glycemic control dramatically raises the incidence of hypoglycemia. In parallel the incidence of severe hypoglycemia also increases. Better glucose control regimens are therefore needed to reduce the incidence of hypoglycemia during tight glycemic control.

Table 1 Mean blood glucose values (mmol/l) and percentage of patients developing (severe) hypoglycemia