Previous research has linked type-2 diabetes to an increased risk of cognitive decline and severe hypoglycaemic episodes to poorer memory.
For this latest study, researchers studied 61 people who had mild cognitive impairment and were aged over 65. Over a four-year period, 19 of the participants developed dementia.
Diabetes was associated with a 2.9-times increased risk of developing dementia. Ten (16 per cent) of those who completed the study had diabetes. But, of those who developed dementia, seven (37 per cent) had diabetes.
The researchers said that identification of those at risk of progression to dementia might help to target early treatment.