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Mechanisms underlying stress-induced hyperglycemia in critically ill patients

Farshad Kajbaf, Mojtaba Mojtahedzadeh and Mohammad Abdollahi

Critical illnesses associate with alteration in metabolic status. Insulin resistance and enhanced blood glucose levels occur during stressful situations, such as acute illnesses. These disturbances associate with poor prognostic events. Intensive insulin therapy and maintaining normoglycemia reduce the morbidity and mortality rate in critically ill patients. We aim to give an overview of the current insights in hyperglycemia and insulin resistance in critical illnesses. A search of the literature was conducted using Pubmed articles in English. Most of the recent and relevant articles were studied, reviewed and summarized with categorization of causes, pathophysiology and adverse events. To introduce better conception regarding stress-induced hyperglycemia and its management, the most viable mechanisms and therapeutic goals are discussed. Hyperglycemia and insulin resistance are common in critically ill patients, particularly in trauma, postmyocardial infarction, following major surgery and among those with sepsis. These complications occur in patients with or without a history of diabetes. Multiple pathogenic mechanisms, such as increased release of proinflammatory cytokines and counterregulatory hormones, have been suggested. The resulting metabolic alteration is associated with significant adverse events and poor prognostic outcomes. Strict glycemic control and intensive insulin therapy could improve the survival rate in critically ill patients. Tight glycemic control by intensive insulin therapy has a pivotal role in the treatment of such patients. Every medication or intervention that could prevent the inflammatory process and insulin resistance might be considered as therapeutic strategies for the improvement of critically ill patients with acute hyperglycemia. Hyperglycemia in critical illnesses The relationship between stressful situations in critically ill patients (CIPs) and acute hyperglycemia was first described in the late 19th Century [1]. Stress-induced hyperglycemia was thought of as an adaptive and even beneficial neurohormonal response to support the energy requirements of insulin-independent cell types, such as brain cells and phagocytes [1]. With high prevalence, hyperglycemia and insulin resistance are associated with poor outcome in a wide spectrum of CIPs [2–5]. Therefore, tight glycemic control could improve the prognosis of these patients and decrease adverse events. Intensive insulin therapy & tight glycemic control in CIPs Previously, glycemic control has not been seriously considered in the intensive care unit (ICU), except in diabetic patients or those with a persistently high glucose level above 200 mg/dl. Results from studies after 2000 demonstrated that tight glycemic control may improve the outcomes of CIPs via a reduction of systemic infection, frequency