Effect of Different Enteral Nutrition Formulas on Glucose Homeostasis

To assess whether enteral nutrition fomulas based either on fat or glucose influence glucose homeostasis differently in critically ill medical patients. All patients are admitted to a tertiary ICU and require mechanical ventilation.

Resting energy expenditure is assessed at baseline in the fasting state by indirect calorimetry. Total energy demand is calculated and patients are randomized to receive fat-based or glucose-based nutrition which is administered continously for 7 days. Indirect calorimetry is repeated on days 3 and 7 under continous nutrition. During the study period, various parameters of glucose homeostasis are assessed. Daily, there will be at least 3 measurements of blood glucose, more if the treating physician deems it necessary. Daily average glucose, daily glucose variability, overall area under the curve for glucose are calculated. Furthermore, energy intake by nutrition, medications (i.e. propofol), and glucose infusion, as well as substrate intake, and insulin demand per 24hrs are determined daily. Adverse effects such as episodes of hyper- or hypoglycemia, cholestasis, hypertriglyceridemia, diarrhea, vomiting, and the amount of gastric residual volume are noted.