It remains unknown whether diabetes mellitus is a risk factor for mild cognitive impairment (MCI).
To investigate the association of diabetes mellitus with MCI using a population-based case-control design.
Design, Setting, and Participants
Our study was conducted in subjects aged 70 through 89 years on October 1, 2004, who were randomly selected from the Olmsted County, MN, population.
Main Outcome Measure
We administered to all participants the Clinical Dementia Rating Scale, a neurological exam, and a neuropsychological evaluation including 9 tests in 4 cognitive domains to diagnose normal cognition, MCI, or dementia. We assessed history of diabetes, diabetes treatment, and complications by interview and we measured fasting blood glucose. History of diabetes was also confirmed using a medical records-linkage system.
We compared 329 patients with MCI to 1640 subjects free of MCI and of dementia. The frequency of diabetes was similar in subjects with MCI (20.1%) and in subjects without MCI (17.7%; odds ratio [OR], 1.16; 95% confidence interval [CI], 0.85-1.57). However, MCI was associated with onset of diabetes before age 65 years (OR, 2.20; 95% CI, 1.29-3.73), diabetes duration ≥10 years (OR, 1.76; 95% CI, 1.16-2.68), treatment with insulin (OR, 2.01; 95% CI, 1.22-3.31), and presence of complications (OR, 1.80; 95% CI, 1.13-2.89) after adjustment for age, sex, and education. Analyses using alternative definitions of diabetes yielded consistent findings.
These findings suggest an association between earlier onset, longer duration, and greater severity of diabetes and MCI.