Disability in patients with multiple sclerosis: influence of insulin resistance, adiposity, and oxidative stress

The aims of the present study were to report the prevalence of insulin resistance (IR) in patients with multiple sclerosis (MS); to verify differences in metabolic and inflammatory biomarkers, and oxidative stress in patients with MS with or without IR; and to assess if IR and adiposity are associated with disability in these patients.

The study enrolled 110 patients with MS and 175 healthy individuals. Patients with MS were divided in those with IR (n = 44) and those without (n = 66). Metabolic and inflammatory markers, oxidative stress, and disability were evaluated by the Extended Disability Status Scale (EDSS).

IR prevalence was verified in 40% of the patients with MS and in 21.1% of the control group (odds ratio, 2.48; 95% confidence interval, 1.469-4.210; P = 0.0006). Patients with the disease and IR showed higher EDSS (P = 0.031), interleukin (IL)-6 (P = 0.028), IL-17 (P = 0.006), oxidative stress evaluated by tert-butyl hydroperoxide-initiated chemiluminescence (P = 0.029), and advanced oxidation protein products (P = 0.025) than those patients without IR. The multivariate analysis showed that disability was associated with IR evaluated by homeostasis model assessment of insulin resistance (P = 0.030) and adiposity evaluated by waist circumference (P = 0.0179) and body mass index (P = 0.0033).

This is the first study to demonstrate an increase IR prevalence and the association between IR and adiposity with disability assessed by EDSS in patients with MS. IR seems to be associated with chronic inflammatory process and oxidative stress in patients with MS. More studies are warranted to elucidate the mechanisms by which IR and adiposity could contribute to the progression and disability in patients with MS.