Insulin resistance in critical illness: consequences for nutrition therapy and glucose management

Critically ill patients usually develop insulin resistance and hyperglycemia, which is aggravated by early parenteral nutrition. In observational studies, the lowest mortality risk associates with glucose concentrations close to the antecedent average glucose level. This review summarizes the most recent evidence regarding glucose control in critical illness.

Although pioneer randomized controlled trials showed morbidity and mortality benefit by normalizing blood glucose in intensive care, the largest multicenter randomized controlled trial found increased mortality. Differences in glucose targets, the accuracy of the glucose control protocol, and differences in feeding strategy may explain these differences.Recent randomized controlled trials investigating the impact of individualized glucose control did not show benefits of targeting individualized or looser glucose values in critically ill patients with poorly controlled diabetes.

It remains unclear whether tight glucose control in critical illness is beneficial or not in the absence of early parenteral nutrition, which is currently being studied in the multicenter TGC-fast randomized controlled trial. Without new evidence, it seems prudent to avoid severe hyperglycemia and hypoglycemia in all patients.