Medical researchers say there is a lack of awareness about the link between type two diabetes and dementia.
Campaigners are raising awareness about the growing numbers with the condition in Ireland, to mark World Diabetes Day.
Dr Catherine Dolan from Trinity College says diabetes sufferers can protect themselves against developing dementia.
She said: "Increasing their physical activity, not consuming excess alcohol, watching their weight and watching things like blood pressure having that monitored, treated.
"These are things that will ultimately reduce your risk of getting dementia later in life."