In this study, we investigated whether greater engagement in leisure activities and a richer social network may compensate for the increased risk of dementia in older adults with diabetes. During 10-year follow-up, diabetes was associated with a 2-times greater risk of dementia, especially of vascular origin. However, this increased dementia risk appeared to be mitigated by active engagement in leisure activities or a rich social network. We estimated that if all older adults with diabetes in our cohort had an active lifestyle, 48% of diabetes-related dementia cases could be prevented. These findings highlight that an active and socially integrated lifestyle could represent a key preventive strategy for dementia, especially in high-risk people, such as those affected by diabetes (Marseglia et al., Diabetes Care 2019).