Impact of Diabetes Mellitus on Surgical Outcomes in Degenerative Cervical Myelopathy: A Prospective Multicenter Study

Prospective multicenter cohort study. To comprehensively evaluate the impact of diabetes mellitus (DM) on surgical outcomes, perioperative complications, and patient-reported outcomes in patients undergoing surgery for degenerative cervical myelopathy (DCM). Both DM and DCM are age-related conditions, and their coexistence has become increasingly common with the aging population. DM is associated with microvascular and metabolic disturbances that may impair neurological recovery and wound healing. Previous studies have yielded inconsistent results, largely due to small sample sizes, retrospective designs, and inadequate adjustment for confounders. A total of 875 patients with DCM, including 200 with DM, were prospectively enrolled across 10 high-volume centers in Japan. Clinical outcomes, including the JOA score, SF-36, Neuropathic Pain Symptom Inventory, and JOA Cervical Myelopathy Evaluation Questionnaire, were evaluated before surgery and at two years after surgery. Perioperative complications were recorded within 30 days after surgery. Clinical and surgical outcomes were analyzed using multivariable statistical models adjusting for demographic and surgical confounders, and the association between preoperative HbA1c and outcomes was examined within the diabetic cohort. Patients with DM were older and had higher BMI than those without DM. After statistical adjustment, DM was not associated with significant differences in postoperative neurological recovery, quality of life, pain, or perioperative complications. Within the diabetic cohort, higher HbA1c levels were modestly associated with smaller improvements in JOA scores (β = -0.111, P = 0.045), but no significant correlations were found with other outcomes or complication rates. DM did not adversely affect surgical or patient-reported outcomes in patients with DCM when perioperative glycemic control was appropriately maintained. These findings suggest that well-managed DM should not be considered a contraindication to surgical treatment for DCM and provide reassurance for clinicians and patients in shared decision-making.