Different Enteral Nutrition Formulas Have No Effect on Glucose Homeostasis but on Diet-induced Thermogenesis in Critically Ill Medical Patients: a Randomized Controlled Trial

Background/objectives: Hyperglycemia is common in critically ill patients and associated with increased mortality. It has been suggested that different nutrition formulas may beneficially influence glucose levels in surgical intensive care patients. In this prospective randomized clinical cohort study we investigated glucose homeostasis in response to different enteral nutrition formulas in medical critically ill patients.

Subjects/methods: 60 medical critically ill patients were randomized to receive continuous fat-based (group A, n = 30) or glucose-based enteral nutrition (group B, n = 30) for seven days. Indirect calorimetry was performed to determine energy demand at baseline and on days 3 and 7. Glucose levels and area under the curve (AUC), insulin demand, glucose variability, and calorie and substrate intake per 24 h were assessed for 7 days.

Results: Over the course of 7 days patients had similar average daily glucose (p = 0.655), glucose AUC (A: 758 (641-829) mg/dl/day vs B: 780 (733-845) mg/dl/day, p = 0.283), similar overall insulin demand (A: 153.5 (45.3-281.5) IE vs B: 167.9 (82.3-283.8) IE, p = 0.525), and received similar amounts of enteral nutrition per 24 h. Resting energy expenditure was similar at baseline (A: 1556 (1227-1808) kcal/day vs B: 1563 (1306-1789) kcal/day, p = 0.882) but energy expenditure increased substantially over time in group A (p < 0.0001), but not in group B (p = 0.097).

Conclusion: Fat-based and glucose-based EN influence glucose homeostasis and insulin demand similarly, yet diet-induced thermogenesis was substantially higher in critically ill patients receiving fat-based enteral nutrition.