title: Association between diabetes and amyotrophic lateral sclerosis in Sweden.
abstract: OBJECTIVE
  Energy metabolism is altered in patients with amyotrophic lateral sclerosis (ALS) but the role of diabetes is largely unknown.
  
  
  METHODS
  A population-based case-control study was conducted of 5108 ALS cases and 25,540 individually matched population controls during 1991-2010. Information on ALS and pre-existing diabetes was retrieved from the Swedish Patient Register to explore the association of ALS with diabetes overall and with insulin-dependent or non-insulin-dependent diabetes specifically. Variation of the association by diabetes duration and age was also studied.
  
  
  RESULTS
  In total, 224 ALS cases (4.39%) and 1437 controls (5.63%) had diabetes before the index date, leading to an overall inverse association between diabetes and ALS risk [odds ratio (OR) 0.79, 95% confidence interval (CI) 0.68-0.91]. The association was strong for non-insulin-dependent diabetes (OR 0.66, 95% CI 0.53-0.81) but not for insulin-dependent diabetes (OR 0.83, 95% CI 0.60-1.15) and varied as a function of diabetes duration, with the strongest association observed around 6 years after first ascertainment of diabetes. The association was age-specific; the inverse association was noted only amongst individuals aged 70 or older. In contrast, for younger individuals (<50 years), pre-existing insulin-dependent diabetes was associated with a higher ALS risk (OR 5.38, 95% CI 1.87-15.51).
  
  
  CONCLUSIONS
  Our study suggests that there is an association between diabetes and ALS, and highlights the importance of taking into account age, insulin dependence and diabetes duration. Future studies should explore whether the association is independent of body mass index.
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: D
authors.initials: D
authors.lastname: Mariosa
authors.affiliation: Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA.
authors.forename: F
authors.initials: F
authors.lastname: Kamel
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.|Department of Statistics and Quantitative Methods, University of Milano-Bicocca, Milan, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Bellocco
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: W
authors.initials: W
authors.lastname: Ye
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: F
authors.initials: F
authors.lastname: Fang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000690:Amyotrophic Lateral Sclerosis / Q000453:epidemiology*; D016022:Case-Control Studies; D015897:Comorbidity; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology*; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012042:Registries; D013548:Sweden / Q000453:epidemiology
keywords: amyotrophic lateral sclerosis; diabetes; epidemiology; insulin dependence; metabolic and endocrine disorders; motor neuron disease; neurological disorders; neuromuscular diseases; research methods