This descriptive study will utilize retrospective chart review to examine factors associated with hypoglycemia. Charts from 700 subjects who experienced blood glucose values less than 70 mg/dl primarily in the preoperative and postanesthesia care units at William Beaumont Hospital-Royal Oak will be reviewed. Another 1600 charts will be screened for subsequent intraoperative hypoglycemia: 800 that had low normal preoperative glucose values and 800 that had high preoperative values (with likelihood of insulin therapy).