Abstract
Hyperglycemia in critically ill patients is frequently associated with an adverse clinical outcome but used to be considered an adaptive stress response and a marker of illness severity. Recent clinical and experimental studies, however, suggest a causal relationship. Tight glycemic control with an insulin infusion reduces mortality and improves the organ function of critically ill subjects. Experimental data point to the importance of glycemic control, irrespective of the insulin level. Potential underlying mechanisms include the reduction of oxidative stress and inflammation, the protection of endothelial and mitochondrial function and the prevention of apoptosis.