ABSTRACT: Retrospective database analysis.To assess the effect glycemic control has on perioperative morbidity and mortality in patients undergoing elective degenerative lumbar spine surgery.Diabetes mellitus (DM) is a prevalent disease of glucose dysregulation that has been demonstrated to increase morbidity and mortality after spine surgery. However, there is limited understanding of whether glycemic control influences surgical outcomes in patients with DM undergoing lumbar spine procedures for degenerative conditions.The Nationwide Inpatient Sample was analyzed from 2002 to 2011. Hospitalizations were isolated on the basis of International Classification of Diseases, Ninth Revision, Clinical Modification, procedural codes for lumbar spine surgery and diagnoses codes for degenerative conditions of the lumbar spine. Patients were then classified into 3 cohorts: controlled diabetic, uncontrolled diabetic, and nondiabetic. Patient demographic data, acute complications, and hospitalization outcomes were determined for each cohort.A total of 403,629 (15.7%) controlled diabetic patients and 19,421 (0.75%) uncontrolled diabetic patients underwent degenerative lumbar spine surgery from 2002 to 2011. Relative to nondiabetic patients, uncontrolled diabetic patients had significantly increased odds of cardiac complications, deep venous thrombosis, and postoperative shock; in addition, uncontrolled diabetic patients also had an increased mean length of stay (approximately, 2.5 d), greater costs (1.3-fold), and a greater risk of inpatient mortality (odds ratio=2.6, 95% confidence interval=1.5-4.8, P<0.0009). Controlled diabetic patients also had increased risk of acute complications and inpatient mortality when compared with nondiabetic patients, but not nearly to the same magnitude as uncontrolled diabetic patients.Suboptimal glycemic control in diabetic patients undergoing degenerative lumbar spine surgery leads to increased risk of acute complications and poor outcomes. Patients with uncontrolled DM, or poor glucose control, may benefit from improving glycemic control prior to surgery.3.