Higher Blood Sugar Tied to Dementia Risk

Higher glucose levels had a significant association with an increased risk of dementia in older, nondiabetic individuals, investigators reported.

Nondiabetic patients who developed dementia had a mean blood glucose level of 115 mg/dL in the preceding 5 years compared with 100 mg/dL in similar patients who did not have dementia. The higher levels were associated with almost a 20% increase in the hazard for dementia, reported Paul K. Crane, MD, of the University of Washington in Seattle, and colleagues.

Adding to the established association between diabetes and dementia, diabetic patients who subsequently developed dementia also had significantly higher average glucose levels as compared with diabetic patients who did not develop dementia (P=0.002), they wrote online in the New England Journal of Medicine.

"We found that higher glucose levels were associated with an increased risk of dementia in populations without and with diabetes," Crane's group stated. "The findings were consistent across a variety of sensitivity analyses."
"These data suggest that higher levels of glucose may have deleterious effects on the aging brain," they added. "Our findings underscore the potential consequences of temporal trends in obesity and diabetes and suggest the need for interventions that reduce glucose levels."
Though consistent with much of the literature on dementia, the findings conflict with those of another recent study, which showed an association between dementia and hypoglycemia.
Diabetes is a recognized risk factor for dementia, and obesity is the leading risk factor for diabetes. However, the relationship among obesity, diabetes, and dementia has remained unclear, as studies of the association have yielded mixed results. In an effort to bring some clarity to the subject, Crane and colleagues retrospectively evaluated longitudinal clinical data on a large prospective cohort.
The study included 2,581 dementia-free individuals randomly selected from the Group Health Cooperative. All participants were 65 or older at enrollment from 1994 through 1996. An additional 811 participants enrolled from 2000 through 2002. Participants were asked to return at 2-year intervals for dementia evaluation, and 2,067 of the participants had at least one follow-up visit.