Critically ill patients are on high risk for increased serum glucose levels, leading to more comorbidity and higher mortality risk. In patients with severe sepsis and septic shock hyperglycemia is a typical finding. However the need of insulin therapy is associated with an increased risk of hypoglycemia. Newly developed technologies for continuous glucose monitoring in critically ill patients may improve glycemic control and reduce glucose variability. The investigators will perform continuous glucose monitoring in critically ill patients on ICU. Measurements will be done for a period of 72h per patient. The investigators aim is to evaluate accuracy feasibility and acceptance of these methods. To analyze accuracy sensor glucose levels will be validated due to arterial blood gas measurements with the blood gas analyzer. The investigators will investigate the influence of several factors like oedema, perspiration, BMI, body temperature, pH-value application of vasoconstrictors on accuracy and feasibility of the particular system. Furthermore Nursing staff will be given a questionnaire to identify acceptance.

Inclusion Criteria:

• critically ill patients with expected ICU stay for more than 72 hours
• informed consent by the patients or legal proxy

Exclusion Criteria:

• age < 18
• no informed consent by the patients or legal proxy
• pregnancy
• infaust prognosis