Type 2 diabetes mellitus, antidiabetics, and the risk of amyotrophic lateral sclerosis

Background: Research on the link between Type 2 Diabetes mellitus (T2DM) and amyotrophic lateral sclerosis (ALS) has produced mixed results. The potential role of antidiabetic medications in ALS etiology is also unclear. To contribute to these discussions, we aimed to examine the connections between T2DM, antidiabetic medications, and ALS using data from a large Israeli health fund. Methods: A total of 504 ALS cases diagnosed in 2002–2018 and 42,873 matched controls were considered in this population-based nested case-control study. T2DM was ascertained using diagnosis codes, laboratory test results, and medication use history, employing a 3-year lag from initial ALS diagnosis date to minimize chances for reverse causation. Multivariable-adjusted odds ratios (OR) were estimated for the association between T2DM, antidiabetic medications, and ALS. Results: T2DM overall was not linked with ALS (multivariable-adjusted odds ratio (OR) = 0.94, 95% confidence interval (CI): 0.72–1.23). However, T2DM with a history of insulin use showed a protective association with ALS (OR = 0.29; 95% CI = 0.09–0.92) compared to the non-T2DM group. A similar trend of protective associations with ALS was observed for T2DM with history of use of other antidiabetic medications, but none were statistically significant, and all associations were further attenuated after adjusting for insulin use. Conclusions: We observe a potential protective effect of T2DM-linked insulin use on risk of ALS. Although caution is necessary due to the limited number of ALS cases with insulin exposure, the observed protective association may suggest a biological pathway worth exploring for future therapeutic development.