Age of type 2 diabetes onset as a risk factor for dementia: A 13-year retrospective cohort study

Abstract

Aims

To examine whether age at type 2 diabetes onset is an independent predictor of dementia risk.

Methods

Retrospective cohort drawn from healthcare administrative records of all inhabitants within Romagna’s catchment area, Italy, with an estimated onset of type 2 diabetes in 2008–2017 and aged ≥ 55, with follow-up until 2020. Time to dementia or censoring was estimated with the Kaplan–Meier method, using diabetes onset as the time origin. Age groups were compared with the log-rank test. Multivariable competing-risks analysis was used to assess predictors of dementia.

Results

In patients aged ≥ 75 years, dementia-free survival (DFS) declined to below 90 % within five years and linearly decreased to 68.8 % until the end of follow-up. In contrast, DFS for those aged 55–64 years showed a marginal decrease, reaching 97.4 % after 13 years. Competing-risks regression showed that individuals aged ≥ 75 and 65–74 had a significantly higher risk of dementia compared to those aged 55–64 years. Having more comorbidities at diabetes onset and initial treatment with ≥ 2 antidiabetics were clinical predictors.

Conclusions

Later age at onset of diabetes is strongly associated with dementia. A better understanding of the diabetes–dementia relationship is needed to inform strategies for promoting specific healthcare pathways.