The purpose of this study is to determine the safety and accuracy of the Real-Time Continuous Glucose monitoring System (RT-CGMS)in measuring glucose in patients scheduled for surgery; before, during and after surgery.

Rationale:Strict glycaemic control improves outcome of critically ill patients. Real Time Continuous Glucose monitoring System (RT-CGMS) is a novel system which can provide health care professionals with real time information about the blood glucose level without the need for multiple invasive measurements. Furthermore, with continuous monitoring it is possible to identify trends in glycaemic profiles. Its accuracy and safety have never been tested in a population of patients admitted to an intensive care unit.

Objective:To investigate the accuracy and safety of the RT-CGMS in patients scheduled for elective cardiac surgery. Our secondary objective is to define the possible factors interfering with reliable and adequate glucose measurements and to investigate the effect of RT-CGMS on glucose control.

Study design: Open label, randomised controlled trial. Study population:Patients scheduled for elective cardiac surgery. Intervention:After informed consent and randomisation, all patients will have the RT-CGMS inserted pre-operatively. In one group (Control group; 15 subjects), the RT-CGMS will be blinded, so that no information on blood glucose values measured and stored by the RT-CGMS will be available to care-givers, investigators or patients during the study period. In the other group (Active group, 15 subjects), the RT-CGMS will not be blinded. The system will alert whenever a glucose level falls below or rises above preset values. Sensor values are not intended to be used directly for making therapy adjustments. Whenever a value is below or above the preset value, the blood glucose level will be measured using separate blood analysis and therapy adjustments based on this value will be done according to the (ICU) protocol.

Study endpoints: Correlation between data obtained with the RT-CGMS and the conventional method. Degree of glucose control defined as the time spent in normoglycaemia, hypoglycaemia and hyperglycaemia, as recorded both with sensor measurements and ward measurements. Occurrence of significant clinical events and its effect on RT-CGMS.

Inclusion Criteria:

• Patients scheduled for elective cardiac surgery
• Age >18 years
• Both patients with diabetes mellitus as non-diabetic patients are eligible

Exclusion Criteria:

• Failure to obtain informed consent
• pre-admission insulin treatment for diabetes mellitus