CHICAGO—Earlier onset, longer duration, and greater severity of diabetes may be associated with mild cognitive impairment (MCI), according to research presented at the 60th Annual Meeting of the American Academy of Neurology. “Our findings emphasize the importance of good control of diabetes and diabetes prevention by reduction of obesity,” said Rosebud O. Roberts, MD, Associate Professor of Epidemiology at the Mayo Clinic in Rochester, Minnesota.
Dr. Roberts and colleagues assessed the association between diabetes and markers of diabetes severity with MCI in a population-based cohort. Individuals ages 70 to 89 from Olmsted County, Minnesota, were randomly selected from an enumeration of the population and invited to participate in a longitudinal study of aging.
Participants underwent a structured interview, which included the Clinical Dementia Rating Scale and the Functional Assessment Questionnaire, a neurologic evaluation, and neuropsychologic testing. A panel of physicians, neuropsychologists, and nurses reviewed the information and assigned diagnoses of normal cognition, MCI, and dementia. A history of diabetes, diabetes treatment, and diabetic complications (ie, retinopathy, neuropathy, or nephropathy) was ascertained. Diagnostic criteria included self-reports of physician diagnosis of the disease, treatment for diabetes, or having diabetic complications; or abnormal fasting blood glucose.
Among 1,969 patients without dementia (median age, 80), 20.1% of those with MCI and 17.7% of those without MCI had diabetes. Three hundred fifty-six people (18.1%) were characterized as having diabetes based on self-report of a physician diagnosis, and 410 (20.8%) were characterized based on self-report or abnormal fasting blood glucose. The researchers found no significant association of MCI with diabetes overall; however, after adjusting for age, gender, and education level, there were significant associations with onset of diabetes before age 65 (odds ratio [OR], 2.2), duration of disease of 10 years or longer (OR, 1.76), treatment with insulin (OR, 2.1), and presence of complications (OR, 1.8).
“It appears that in our sample of 70- to 89-year-olds, people whose diabetes is severe and requires treatment with insulin or results in diabetes complications and people who have had diabetes for a long time have a higher likelihood of impairment in their cognitive function (this includes memory and other thinking skills, such as judgment and decision making),” noted Dr. Roberts.
The researchers plan to prospectively examine the role of diabetes as a predictor of MCI. “We need to confirm our findings by following up subjects in our study to determine whether those with diabetes—but no cognitive impairment at enrollment—develop cognitive impairment at a faster rate than people who do not have diabetes,” Dr. Roberts concluded.
—Larry Lubiner