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 .