Cervical spinal cord enlargement and systemic inflammation in diabetic peripheral neuropathy: a cross-sectional MRI study

Diabetic peripheral neuropathy (DPN) is one of the most common and disabling complications of type 2 diabetes mellitus (T2DM). Although traditionally considered a peripheral disorder, recent evidence indicates concomitant central nervous system (CNS) involvement. The systemic immune-inflammation index (SII) has emerged as a biomarker reflecting inflammatory activity in diabetes. This study aimed to assess cervical spinal cord cross-sectional area (CSA) using magnetic resonance imaging (MRI) in diabetic patients with and without DPN and to examine its association with systemic inflammation and metabolic parameters. This retrospective, cross-sectional study included 299 participants: 100 healthy controls, 100 diabetic patients without DPN, and 99 with DPN. Cervical spinal CSA was measured on MRI, and fasting plasma glucose (FPG), glycated hemoglobin (HbA1c), complete blood count parameters, and SII values were analyzed. Intergroup comparisons and correlations were evaluated using nonparametric tests and multivariate models. Both diabetic groups showed significantly higher HbA1c, FPG, and SII levels compared with the control group (p < 0.05). Cervical spinal CSA was significantly greater in diabetic groups, particularly in those with DPN (p = 0.004). CSA correlated weakly and positively with HbA1c and FPG, but not with SII. Diabetic patients, especially with DPN, exhibit cervical spinal cord enlargement accompanied by elevated systemic inflammation. The CSA increase may represent an early phase of neuroinflammation preceding atrophy. Combining MRI-derived CSA with SII may improve early detection and risk stratification, supporting an integrated assessment of central and peripheral neuroinvolvement in diabetes.