NEW EVIDENCE TIES ELEVATED BLOOD SUGAR TO DEMENTIA

The New England Journal of Medicine published a study on August 8 that further ties high blood sugar levels with an increased risk of dementia.   Physicians have recognized a connection between diabetes and an increased risk of dementia, and this study expands on this understanding.  The study’s findings are impressive, due to the number of participants in the study, its duration, and the strong statistical data that suggests that elevated levels of sugar are associated with an increased risk of developing dementia over time.

Details of the Study

The study was started in 1994 in the State of Washington.  It followed 2067 members of an HMO, all of whom were all over the age of 65 at the start of the study.  No participant had had been diagnosed with dementia at the start of the study.  The study followed the participants on average for almost 7 years.

The study participants had their blood glucose measured as part of their normal annual medical care, and researchers had access to blood glucose measurements taken prior to the start of the study as well.   The researchers calculated blood glucose levels using  multiple measurements to provided an average glucose measurement over a three month period,  not just a snap shot on the day the blood was drawn.

The participants were assessed for dementia every two years as well.  The study results were refined by adjusting for other possible causes of dementia including carrying the APOE4 gene, high blood pressure, smoking, levels of exercise, and coronary disease.

Results of the Study

The study results showed that the higher a person’s glucose levels were, the higher the risk of developing dementia.  There was no glucose level at which a person’s likelihood of developing dementia did not continue to go down.  Therefore, it appears that people have an increased risk for dementia if their blood sugar levels are elevated, even it they do not become diabetic.

Implications of this Study 

This study is known as an observational study.  The researchers watched the participants over time, measured their blood chemistries, and reviewed the data to see if there was any correlation between high blood sugar and the development of dementia.  However, the study did not try to understand what about high blood sugar levels might cause dementia.  All it did establish was that there is a connection between the two.  It could be that low blood sugar allows the expression of other characteristics that are protective.  It could be that the association is just a coincidence, or that people with high blood sugar also have another trait that is the causal agent.

Since the study does not establish that high blood sugar causes dementia, it is probably not prudent to rush to reduce one’s blood sugar, and indeed there have not been a flurry of calls by physicians to reduce blood sugar levels as a way to stave off dementia.  However, regular exercise, a balanced diet and normal weight all help to prevent increases in blood sugar levels.  They also are part of a good formula for general well being.

Observational studies that identify a strong association between a disease and a specific trait are usually followed up by other studies that are designed to learn what the causal agent is.  We can look forward to more research in this area.