Hyperglycemia and insulin resistance develop in the majority of severe acute illness and/or injury. One of the main causes of hyperglycemia in critically ill patients is the release of counterregulatory stress hormones and proinflammatory cytokines, in addition to increased production of glucose along with its decreased utilization. Hyperglycemia plays an important role not only in influencing the cascade of inflammatory cytokines, but it also increases oxidative stress. In the past, stress hyperglycemia was thought to be an evolutionary protective, natural adaptive response of the body to current threat, which allows increased entry of glucose into the cells of non-insulin-tissues, thus improving chances for survival. At present, however, this state of insulin resistance, glucose intolerance and hyperglycemia is called "stress diabetes" or "diabetes of injury". Ever since the time of the breakthrough "Leuven" study, which brought significant reduction in morbidity and mortality in surgical critically ill patients with tight glycemic control, hospitals, particularly their intensive care units, have focused on the treatment of hyperglycemia. Although extensive observational data have shown a consistent, almost linear relationship between blood glucose concentrations seen in hospitalized patients and the incidence of adverse clinical results, there have been particular doubts concerning the universality of control, its safety, and pitfalls resulting from hypoglycemia. This controversial debate is currently enriched by the recent international trial - the NICE-SUGAR, whose post-hoc analyses are currently underway. Despite the controversy there is no doubt that the deliberate control of blood glucose control in critically ill patients is justified. It is the insulin application regimen--the insulin protocol per se--that remains the biggest problem in the implementation of glycemic control. Regarding targets, it is necessary to take into account that the best positive effects on outcomes can be anticipated in certain subgroups of critically ill patients, which is currently the subject of further study. Continued streamlining, achieving optimal blood glucose ranges in critically ill patients will allow us to develop and apply computer algorithms that greatly simplify and improve continuous monitoring of blood glucose. Procedures seeking optimal intensive control in critically ill patients are accepted in intensive care units. However, it is undoubtedly necessary to improve monitoring techniques and the quality of biosensors in order to ensure the safety and effectiveness of interventions aimed at reducing blood glucose levels while using advanced protocols. Automatic closed systems are a promise for the future.