Elevated blood sugar tied to dementia, even without diabetes

‘Big 4’ Journal Highlights – New England Journal of Medicine (NEJM) – by Bruce Sylvester – Research published on Aug. 7, 2013 in the New England Journal of Medicine/NEJM indicates that elevated blood sugar levels are associated with increasing dementia risk, even when there is no diagnosis of diabetes.

The investigators evaluated retrospectively 5-year data from 2,000 patients age 65 and older in the Adult Changes in Thought (ACT) study.

“One major strength of this research is that it is based on the ACT study, a longitudinal cohort study, where we follow people for many years as they lead their lives,” said investigators Eric B. Larson, MD, MPH, a senior investigator at Group Health Research Institute in Seattle, Washington. “We combine information from people’s research visits every other year with data from their visits to Group Health providers whenever they receive care. And this gave us an average of 17 blood sugar measurements per person: very rich data.”

They found increasing blood sugar associated with increasing risk of dementia. Among subjects without diabetes, the risk of developing dementia was 18 percent higher for those with an average glucose level of 115 milligrams per deciliter compared to those with an average glucose level of 100 mg/dl.

“The most interesting finding was that every incrementally higher glucose level was associated with a higher risk of dementia in people who did not have diabetes,” said investigator Paul K. Crane, MD, MPH, associate professor of medicine at the University of Washington School of Medicine in Seattle. “There was no threshold value for lower glucose values where risk leveled off.”

Among those with diagnosed diabetes, whose blood sugar levels were generally higher, dementia risk was 40 percent higher for subjects with an average glucose level of 190 mg/dl compared to those with an average glucose level of 160 mg/dl.

The measurements included blood glucose and glycated hemoglobin (HbA1c).

Crane emphasized that these results come from an observational study. He said, “What we found was that people with higher levels of glucose had a higher risk of dementia, on average, than did people with lower levels of glucose. While that is interesting and important, we have no data to suggest that people who make changes to lower their glucose improve their dementia risk. Those data would have to come from future studies with different study designs.”