Metabolic Dysregulation, Inflammation, and Median Nerve Dysfunction in Patients with Type 2 Diabetes Mellitus with Carpal Tunnel Syndrome

Carpal tunnel syndrome (CTS) is the most common compressive mononeuropathy. In patients with type 2 diabetes mellitus (T2DM), chronic hyperglycemia, microangiopathy, and systemic inflammation increase the vulnerability of peripheral nerves to compression. This study aimed to assess the relationship between CTS severity and clinical, metabolic, inflammatory, and electrophysiological parameters in patients with T2DM. A cross-sectional study was conducted from June 2023 to June 2024, involving patients diagnosed with T2DM. Electrophysiological assessment of the upper and lower limbs was performed using a four-channel electromyography apparatus. Clinical and anthropometric data and laboratory parameters were obtained, as well as the results of nerve conduction studies (NCS). One hundred and twenty-three patients with T2DM were included in the study. The prevalence of moderate-to-severe forms of CTS was 43.9%, and bilateral involvement was present in 21.95% of patients. Patients with moderate-to-severe CTS had significantly higher hemoglobin A1c (HbA1c) (p = 0.004), glycemia (p < 0.001), and Triglyceride–Glucose Index (p = 0.018) compared with those without CTS/with mild forms. The number of monocytes was significantly higher in the group with moderate-to-severe forms (p = 0.012), suggesting a chronic inflammatory state. In the logistic regression analysis, hemoglobin HbA1c emerged as an independent predictor of CTS severity, with each 1% increase associated with approximately a 60% higher risk of moderate/severe CTS. NCS analysis showed significant correlations between median nerve parameters and those of the lower-limb peripheral nerves, particularly the tibial and sural nerves, suggesting an association with generalized diabetic peripheral neuropathy. Professional activity was significantly associated with moderate-to-severe CTS (OR = 3.5). CTS is a common complication in patients with T2DM and is associated with worse glycemic control, insulin resistance, systemic inflammation, and peripheral neuropathic damage.