Observation of incretin effects during enteral feed transitions of critically ill patients

Abstract

Summary Background & aims Critically ill patients are regularly feed via constant enteral (EN) nutrition infusions. However, the incretin effect or its impact on endogenous insulin concentration remains unclear. This study determines whether there is an EN-driven incretin effect in critically ill patients requiring glycaemic control. Methods Clinically validated, model-based time-variant insulin sensitivity (SI) profiles were identified for 52 non-diabetic patients on Specialized Relative Insulin Nutrition Titration (SPRINT) glycaemic control during transitions off EN (ON/OFF), and back on to EN (OFF/ON). Incretin effects were observable via increased modelled SI after the OFF/ON transition or a decreased SI after the ON/OFF transition. Results Patients exhibited a median −36% (IQR −82% to 24% p = 0.001) reduction after the ON/OFF feed transition, and a median of +32% (IQR −5% to 53%, p = 0.05) rise in measured SI after the OFF/ON transition. However, 32% of patients exhibited increased SI at the OFF/ON transition, and 37% exhibited reduced SI at the ON/OFF transition. The results are likely due to changes in patient condition over the 5–8 h considered outweighing this effect. Blood glucose was the same during both transitions with median shifts of −2% and −3% after the ON/OFF, and OFF/ON transitions (p > 0.5), respectively. Conclusions Results imply a significant incretin effect is observed at a cohort level. The impact was stronger for the OFF/ON transition indicating that this effect may be blunted by long-term continuous EN infusions. These results provide the data to design conclusive studies, and to inform glycaemic control protocol development and implementation.