Is Diabetes Mellitus a Risk or Protective Factor for ALS?



CHICAGO—Diabetes mellitus delays the onset of motor symptoms but is associated with worse cognitive function among patients with amyotrophic lateral sclerosis (ALS), according to Alicia R. Salamone and colleagues. The researchers presented their findings at the 60th Annual Meeting of the American Academy of Neurology.
The 29-year study involved 2,397 patients who were diagnosed with either probable or definite ALS. All patients were tested for diabetes mellitus, and comprehensive neuropsychologic testing was performed in 484 subjects. Diabetes mellitus was found in 7.3% of patients, reported Ms. Salamone, from the Department of Neurology at Baylor College of Medicine in Houston, and coauthors.
The researchers found that patients with ALS and diabetes mellitus did not experience a different duration or faster progression of ALS, as determined with use of the Appel Scale, than did subjects without diabetes mellitus. ALS patients with diabetes performed significantly worse than those without diabetes, however, on measures of intelligence, attention, executive function, episodic memory, semantic memory, and naming.
“Comorbid diabetes mellitus in ALS appears to have a beneficial effect on disease course, as diabetics were found to have a six-year later age of onset, without a faster rate of progression or shorter duration of disease as would be expected,” reported the researchers.
“However, diabetics within this cohort had significantly worse cognitive function. As the normal life expectancy of ALS is about three years, this raises the question of whether diabetes contributes an overall beneficial or negative effect to this disease,” Ms. Salamone and colleagues concluded.

—Pamela Holland-Moritz

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