Comparative Analysis of Postoperative Outcomes in Type 1 Versus Type 2 Diabetes Mellitus Patients Undergoing Spinal Fusion

Background: Spine surgery in diabetic patients presents unique challenges due to impaired healing and metabolic dysfunction. While diabetes is a known risk factor for adverse surgical outcomes, limited data exist comparing complications between type 1 (T1DM) and type 2 diabetes mellitus (T2DM). This study evaluates postoperative outcomes in patients with T1DM versus T2DM undergoing spinal arthrodesis. Materials and Methods: Retrospective cohort analysis was performed using the TriNetX national health research network. Diabetes subtypes were identified using ICD-10 codes and medication profiles. A total of 1261 propensity score-matched patients in each cohort were identified after controlling for demographics, comorbidities, and diabetic severity. A subgroup analysis was performed with 467 cervical and 257 lumbar propensity score-matched pairs. The study analyzed outcomes occurring within 1 year postsurgery including infection, readmission, reoperation, fracture, gait abnormality, muscle weakness/sarcopenia, dorsalgia, and all-cause mortality. Statistical measures included risk differences, risk ratios, odds ratios, and survival analysis. Results: Patients with T1DM exhibited a signifqqicantly higher postoperative infection risk (3.4% vs . 1.2%, P < 0.001; HR: 2.88), spinal fracture risk (3.9% vs . 2.0%, P = 0.008; HR: 2.02), readmission rate (39.0% vs . 11.0%, P < 0.001; HR: 4.19), and reoperation rate (7.6% vs . 2.6%, P < 0.001; HR: 3.04) within 1 year as compared with T2DM. T1DM patients were found to have significantly elevated risk of readmission for both the cervical (28.5% vs . 6.8%; P < 0.001) and lumbar (31.9% vs . 15.0%; P < 0.001) subgroups. One-year all-cause mortality risk remained significantly greater for T1DM as compared with T2DM in cervical (6.2% vs . 2.6%; P = 0.014) and lumbar (5.8% vs . 3.9%; P = 0.009) fusions. Conclusions: T1DM is associated with a greater risk of postoperative infections, readmissions, fractures, gait abnormalities, and reoperations within 1 year postoperatively compared with T2DM. This is more pronounced in larger, multilevel surgeries, while readmission and all-cause mortality remain significant in isolated cervical and lumbar fusion. These findings underscore the need for further mechanistic investigation and tailored perioperative management strategies in diabetic patients undergoing spine surgery to mitigate risks and improve outcomes.