Risk of developing dementia in people with diabetes and mild cognitive impairment

Background Diabetes mellitus is associated with cognitive dysfunction, but it is not clear whether the disorder increases the risk of conversion from mild cognitive impairment to dementia. Aims To determine the association between diabetes mellitus and dementia conversion in people with mild cognitive impairment (Peterson's criteria) in a prospective community-based study. Method People over 65 years old were approached through primary care practices in south London, UK, and those with mild cognitive impairment (n=103) were followed up for 4 years. Presence of diabetes was established from self-report and information from general practitioners. Results Nineteen participants progressed to dementia, with the predominant diagnosis being probable or possible Alzheimer's disease (in 84%). Only diabetes mellitus was associated with progression to dementia (hazard ratio 2.9, 95% CI 1.1-7.3) after adjustment for sociodemographic factors, APOE4, premorbid IQ and other health conditions. Conclusions Diabetes mellitus increases not only the risks of dementia and mild cognitive impairment but also the risk of progression from such impairment to dementia.