This study aimed to assess the relation of early-onset type 2 diabetes (age<55years) versus later in life to the risk of dementia, Alzheimer Disease (AD) dementia and stroke.

This study was based on the Framingham Heart Study Offspring cohort (FHS-OS) which is a community-based prospective cohort. Glycemic status was ascertained at serial examinations over six decades among participants who initially did not have diabetes. Surveillance for incident events including dementia and stroke has been continued for approximately 30 years.

At baseline, there were 142 (5%) subjects with onset of diabetes prior to age 55 years, 172 (6%) subjects with 55–64 years, 349 (11%) subjects over 65 years and 2389 (78%) subjects without diabetes. The risk of dementia, AD and stroke increased with decreasing age of diabetes onset (P<0.05, for trend). Compared with never developing diabetes, early-onset diabetes conferred a higher risk of all dementia, AD dementia and stroke [HR 2.86(1.16–5.51) for dementia; HR 2.42(1.63–4.33) for AD; HR 2.85(1.37–3.98) for stroke]. Whereas later-onset diabetes was only associated with greater risk for stroke, neither dementia nor AD.

Early-onset diabetes was stronger associated with an increased risk of all dementia, AD dementia and stroke than later-onset.