The role of type 2 diabetes in the association between habitual glucosamine use and dementia: a prospective cohort study

BACKGROUND: Growing evidence has showed an association between habitual glucosamine use and type 2 diabetes (T2D). However, the effect of habitual glucosamine use on risk of dementia remains poorly understood. Our study aimed to examine the association between glucosamine use and risk of dementia and further to identify the mediating role of T2D in the association. METHODS: A total of 495,942 participants from UK Biobank who completed a questionnaire on habitual glucosamine use were included at baseline (2006–2010) and then followed up for incidence of dementia until 2020. Cox proportional hazard regressions were performed to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for incident dementia. Markov multi-state models were used to explore the role of incidence of T2D during the follow-up in the association. RESULTS: Overall, 18.80% of the participants reported habitual use of glucosamine at baseline. A total of 6831 dementia events were recorded during a median follow-up of 11 years. In fully adjusted models, habitual glucosamine use was associated with a significantly lower risk of dementia (HR = 0.87, 95% CI: 0.82–0.93). Multi-state models showed that the association between glucosamine use and dementia was mediated by the incidence of T2D during the follow-up (HR of dementia without T2D: 0.92, 95% CI: 0.86–0.99; HR of post-T2D dementia: 0.79, 95% CI: 0.67–0.93). CONCLUSIONS: Our findings reveal that habitual use of glucosamine supplement is associated with a lower risk of dementia, which might be explained by incidence of T2D. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13195-022-01137-x.