Diabetes, insulin, and development of acute lung injury

Recently, many studies have investigated the immunomodulatory effects of insulin and glucose control in critical illness. This review examines evidence regarding the relationship between diabetes and the development of acute lung injury/acute respiratory distress syndrome (ALI/ARDS), reviews studies of lung injury related to glycemic and nonglycemic metabolic features of diabetes, and examines the effect of diabetic therapies.

A MEDLINE/PubMed search from inception to August 1, 2008, was conducted using the search terms acute lung injury, acute respiratory distress syndrome, hyperglycemia, diabetes mellitus, insulin, hydroxymethylglutaryl-CoA reductase inhibitors (statins), angiotensin-converting enzyme inhibitor, and peroxisome proliferator-activated receptors, including combinations of these terms. Bibliographies of retrieved articles were manually reviewed.

Available studies were critically reviewed, and data were extracted with special attention to the human and animal studies that explored a) diabetes and ALI; b) hyperglycemia and ALI; c) metabolic nonhyperglycemic features of diabetes and ALI; and d) diabetic therapies and ALI.

Clinical and experimental data indicate that diabetes is protective against the development of ALI/ARDS. The pathways involved are complex and likely include effects of hyperglycemia on the inflammatory response, metabolic abnormalities in diabetes, and the interactions of therapeutic agents given to diabetic patients. Multidisciplinary, multifaceted studies, involving both animal models and clinical and molecular epidemiology techniques, are essential.