Effectiveness of tight glycemic control in the medical Intensive Care Unit: a systematic review

Abstract

Background Intensive Insulin Therapy (IIT) as a means to achieve tight glycemic control (TGC) has become controversial in the medical intensive care unit (ICU) or mixed medical-surgical ICU. The question still remains as to the benefit of tight glycemic control in all patient populations and the optimal target blood glucose range. Review questions/objectives What is the effectiveness of tight glycemic control on adverse outcomes in non-surgical critically ill patients? More specifically, what is the rate of hypoglycemia and mortality in medical intensive care patients who are treated with tight glycemic control regimens? What should be the recommended blood glucose range for patients in a non-surgical, medical ICU? Inclusion criteria Types of participants This review included studies with patients 18 years of age and older, females and males, all types of conditions or diseases, and all stages of severity admitted to a critical care or intensive care unit that required hyperglycemia management and had not had a surgical procedure. Types of intervention(s)/phenomena of interest This review included studies that evaluated the effectiveness of tight glycemic control or intensive insulin therapy as compared to conventional, moderate or liberal insulin therapy. Types of outcomes This review considered studies that included the following outcome measures: frequency and severity of hypoglycemia, and any type of reported mortality. Types of studies This review included only randomized controlled trials which met all of the inclusion criteria. Search strategy A three-step search strategy was utilized find both published and unpublished studies in English language only. An initial limited search of MEDLINE and CINAHL was completed followed by analysis of the text words contained in the title and abstract, and of the index terms used to describe the article. A second search using all identified keywords and index terms was then undertaken across all included databases. Thirdly, the reference list of all identified reports and articles was searched for additional studies. Methodological quality The reviewers used the JBI Critical Appraisal Checklist for Randomised Controlled Trials to assess methodological quality. Data collection Data was extracted using The JBI Data Extraction Form for Experimental/Observational studies. Data synthesis Due to the heterogeneous nature of the study methods, the findings of this systematic review are presented in a narrative summary. Meta-analysis was unable to be performed. Results The four studies in this systematic review include patients with a multitude of diagnoses and comorbidities which further complicates treatment and outcomes assessment. Until further studies prove otherwise, nonsurgical patients requiring glycemic management are best served with less intensive regimens than their surgical counterparts. Conclusions Further research is needed to establish clear, evidence-based guidelines for the management of hyperglycemia in all ICU patient populations. Implications for practice Based on the results of this review and data from the four included studies, glycemic management for medical patients in the intensive care unit should differ from that of surgical patients. Blood glucoses should be kept between 110-180mg/dL in order to prevent the unwarranted effects of hypoglycemic episodes. Implications for research Published studies compare outcomes for patients with dissimilar medical conditions and current protocols for glycemic management are still based on the results of surgical patient trials. Measurements for interventions and outcomes need to be standardized in order to ensure proper comparison and application of results.