Hyperglycemia and Dementia Risk

In Seattle, researchers have found that higher blood sugar levels are associated with higher dementia risk, even among people who do not have diabetes.3 In a study that included more than 2,000 patients aged 65 years and older, researchers found that blood sugar levels averaged over a 5-year period were associated with an increasing risk for dementia.

Results indicated that the risk for dementia was 18% higher for people with an average glucose level of 115 mg/dL compared with those with an average glucose level of 100 mg/dL. Additionally, the dementia risk was 40% higher for patients with diabetes with an average glucose level of 190 mg/dL compared with those with an average glucose level of 160 mg/dL. 

Lead study author Paul Crane, MD, MPH, who is an associate professor of medicine at the University of Washington in Seattle, said the most interesting finding was that every incrementally higher glucose level was associated with an increased risk for dementia in people who did not have diabetes. However, there was no threshold value for lower glucose values where risk leveled off.

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“The cells in the hippocampus appear to be extremely sensitive to glucose levels,” said Dr. Crane. “There have been an increasing number of studies that have confirmed that glucose levels appear to be associated with various brain outcomes, and this reinforces blood sugar as a clinically significant risk factor. We have to find out if this is a factor that is amenable to interventions and whether exercise can moderate it. The field has moved in that direction, and that is gratifying.”

He said endocrinologists in particular may want to have a discussion about this with their patients with diabetes. Dementia is something that many adults fear, Dr. Crane noted, which may motivate these patients to take a more active role in the management of their disease.

“Dementia is an outcome that many older patients are motivated by more so than heart disease. There is a lot of fear about dementia, so that is something that an endocrinologist would want to go over with their patients,” Dr. Crane said in an interview with Endocrinology Advisor

“I think endocrinologists should be thinking about brain health when conceptualizing the patient. They have to deal with a variety of things such as cardiovascular health and kidney health, and those are things that endocrinologists think about, but brain health is becoming an issue of increasing importance.”

Age, Gender Differences

A large population-based study of randomly selected participants in Germany also confirms that brain health is a paramount issue that must be addressed in patients with diabetes, with researchers finding that MCI occurred twice as often in individuals diagnosed with type 2 diabetes.4

Interestingly, however, this strong association was only observed in middle-aged participants (50 to 65 years), whereas in older participants (66 to 80 years), the association vanished. The researchers also found significant gender differences.

The Heinz Nixdorf Recall (Risk Factors, Evaluation of Coronary Calcium and Lifestyle) study is an observational, population-based, prospective study that examined 4,814 participants (50% men) between 2000 and 2003 in the metropolitan Ruhr area in Germany. After 5 years, a second examination was conducted with 90% of the participants taking part. 

Data demonstrated a strong association between type 2 diabetes and MCI and MCI subtypes, but only in middle-aged participants. Further, examination of differences by gender revealed a stronger association of diabetes with amnestic MCI in middle-aged women and, by contrast, a stronger association with non-amnestic MCI in middle-aged men.

Participants were considered amnestic MCI if they had impairment in the memory domain and they were categorized as non-amnestic MCI if they had deficits in non-memory domains.

These results suggest that middle-aged patients with diabetes are particularly vulnerable to MCI, with gender-specific effects on subtypes of MCI. The researchers concluded that this highlights the importance of high-quality treatment of diabetes especially in middle age, not only because of CV damage, but also because it might help to prevent or delay cognitive decline.