With evidence linking surgical morbidity to hyperglycemia (high blood sugar), attention to glucose control is warranted during surgery as well as in the postoperative period. Consequently, measures to prevent and treat hyperglycemia - coupled with fasting status - places patients at considerable risk for perioperative hypoglycemia (low blood sugar). Outpatient patient studies support that profound hypoglycemia can be deleterious and even fatal to patients. 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). Numerous factors believed to be associated with perioperative hypoglycemia will be analyzed including type and duration of diabetes, usual diabetes treatment regimen and alterations on day of surgery, self-reported usual fasting blood sugar range, duration of fasting, type of surgery and anesthesia, co-morbidities, and medications associated with hypoglycemia. Determining factors associated with perioperative hypoglycemia will improve prediction of which patients are at highest risk for hypoglycemia, enabling healthcare providers to institute more conservative insulin therapy when indicated, initiate early maintenance intravenous dextrose, and/ or perform more frequent glucose testing. Identifying associated factors will improve hypoglycemic predictions and interventions which should lead to safer, more effective care for patients with diabetes.