Does Postoperative Glycemic Control Lead to Worse Outcomes in Adult Spinal Deformity Surgery? A Study of Diabetic and Nondiabetic Patients

BACKGROUND AND OBJECTIVES: Postoperative hyperglycemia is a known risk factor of complications after surgery. In patients undergoing adult spinal deformity (ASD) surgery, we evaluated the effect of postoperative hyperglycemia in diabetics and nondiabetics on: (1) medical complications, (2) mechanical complications, and (3) reoperation. METHODS: A retrospective cohort study was performed for patients undergoing ASD surgery from 2009 to 2023 with ≥2-year follow-up. The primary exposure variable was postoperative hyperglycemia. All postoperative glucose values during the index hospitalization were collected. Hyperglycemia was defined as: (1) 2 values > 200 mg/dL or (2) average daily postoperative glucose >140 mg/dL. Primary outcomes included: medical complications, mechanical complications, and reoperation. Univariate and multivariable analyses were performed, controlling for demographics, body mass index, and comorbidities with subanalyses for diabetics and nondiabetics. RESULTS: Of 288 patients undergoing ASD surgery, 56 (19%) were diabetics. The mean age was 63 ± 17 years and 75 (26%) were men. Postoperative hyperglycemia was observed in 63 (22%) patients (54% diabetics and 46% nondiabetics, P < .001). All Patients: Hyperglycemia was associated with an increased risk of distal junctional kyphosis (12.7% vs 0.0%, P < .001) and reoperation because of any mechanical complication on bivariate (41% vs 27%, P = .031) and multivariable analysis (odds ratio: 1.88, 95% CI: 1.00-3.50, P = .049). Diabetics: Hyperglycemia had no association with postoperative complications or reoperations. Nondiabetics: Hyperglycemia was associated with increased risk of reoperation for mechanical complication on bivariate (41% vs 24%, P = .041) and multivariable analyses (odds ratio: 2.60, 95% CI: 1.11-6.08, P = .028). CONCLUSION: Postoperative hyperglycemia was seen in 22% of patients undergoing ASD surgery, 46% of whom were nondiabetics. Hyperglycemia was associated with increased risk of reoperation for mechanical complications, particularly in nondiabetic patients and not in diabetic patients. Tight postoperative glucose control in all patients after ASD surgery may minimize complications.