STUDY DESIGN: Systematic review and meta-analysis. PURPOSE: This meta-analysis aimed to provide a comprehensive evaluation of the impact of diabetes on spinal surgery outcomes. SUMMARY OF BACKGROUND DATA: Diabetes Mellitus is believed to be associated with an increased risk of adverse events during spinal surgery. With the increasing prevalence of diabetes and the increasing number of degenerative spinal procedures, understanding postsurgical expectations and optimal care is essential. METHODS: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic search was conducted across PubMed, EMBASE, Scopus, and the Cochrane Library, selecting studies comparing diabetes and without diabetes who underwent spine fusion surgeries. 18 studies with 118,617 patients were included. The outcomes of interest were the risk of the incidence of spinal pseudoarthrosis and PROMs, including Visual Analog Scale (VAS), Oswestry Disability Index (ODI), EQ-5D and SF-12/36 score. Odds ratios (OR) were calculated for dichotomous variables, mean differences (MD) for continuous variables and Standard Mean Differences (SMD) for continuous variables not sharing the same scale or units. Random effects were used if there was evidence of statistical heterogeneity. RESULTS: Eighteen studies, comprising 118,617 patients, were included in the final analysis. Diabetes patients had a higher incidence of pseudoarthrosis at the lumbar spine (OR 1.13, 95%CI 1.02 to 1.25, P<
0.05). Patients with diabetes also reported increased VAS back/neck pain scores (SMD 0.21, 95%CI 0.14 to 0.28, P<
0.002) and worse ODI outcomes (MD 3.96, 95%CI 3.10 to 4.82, P<
0.002), EQ-5D (MD -0.06, 95%CI -0.08 to -0.03, P<
0.002) and SF-12/36 scores (SMD -2.70, 95%CI -4.99 to -0.41, P<
0.05). CONCLUSION: Patients with diabetes who underwent spinal surgery had a higher incidence of pseudoarthrosis and worse functional outcomes compared to non-diabetic patients. These findings underscore the need for targeted clinical management and preventive strategies for patients with diabetes undergoing these procedures. LEVEL OF EVIDENCE: III.