The role of pre-morbid diabetes on developing amyotrophic lateral sclerosis

Background and purpose: The literature on the association between diabetes and amyotrophic lateral sclerosis (ALS) consists of a limited number of studies. This cohort study was developed in order to assess the role of diabetes on the risk of developing ALS. Methods: The study population was represented by all residents in Turin (Italy) at the beginning of 1996 who participated in the 1991 census, over 14 years of age (n = 727 977) and followed up for ALS occurrence from 1998 to 2014. Presence of diabetes at baseline or during follow-up was ascertained through two Piedmont regional sources: the Diabetes Registry and the Anatomical Therapeutic Chemical Drug Prescription Archive. The risk of ALS was estimated using the Piedmont and Valle d’Aosta ALS Registry (PARALS). The association of diabetes, treated as a time-dependent variable, with ALS onset was estimated through Cox proportional hazard regression models adjusted for age, gender, education and marital status. Results: During follow-up, 397 subjects developed ALS, 24 of whom were already diabetic before ALS onset. Diabetes was associated with a significantly decreased risk of ALS [hazard ratio, 0.30 (95% confidence interval, 0.19–0.45)] without differences in risk by gender, age class or ALS phenotype. Conclusion: The results support the protective role of diabetes toward ALS.