Risk of Diabetes Mellitus in the Myasthenia Gravis: A Systematic Review and Meta-Analysis

Background/Objectives: Myasthenia gravis (MG) comprises an autoimmune disorder marked by muscle weakness and fatigue. MG frequently coexists with other autoimmune conditions, such as diabetes mellitus, which may exacerbate the clinical burden of MG and adversely impact overall quality of life. Methods: This systematic review and meta-analysis aimed to assess the prevalence of diabetes in patients with MG. Following PRISMA guidelines, a comprehensive search was conducted in the MEDLINE PubMed, Scopus, and Google Scholar databases. Results: A total of 11 studies comprising 16,825 patients were included. The pooled prevalence of diabetes among MG patients was 15.6% (95% CI [8.4%, 24.7%]; I² = 99%, p < 0.001). Compared to healthy controls, MG patients had a 1.24-fold increased risk of developing diabetes (95% CI [1.01-1.54], p < 0.001). Meta-regression showed no association between age and diabetes prevalence, although potential publication bias was noted (Egger's test, p = 0.72). Conclusions: This meta-analysis reveals a higher prevalence of diabetes among MG patients, with an elevated risk compared to healthy individuals. These findings suggest that the association between MG and diabetes may be mediated by corticosteroid use, genetic factors, and reduced physical activity. The main limitations of this study are the lack of reported data regarding the type of diabetes and patients' demographic and disease characteristics (MG classification severity and duration and type of treatment). Further studies are needed to investigate the underlying causal mechanisms and to elucidate the relationship between MG and diabetes subtypes.