Tuesday, March 11, 2014

Groundbreaking New Research On Blood Sugar And Dementia

Glucose levels and risk of dementia. New England Journal of Medicine 2013; 369:540-48

Previous research has shown that diabetics have an increased risk of dementia.  This study examines the association between high blood glucose levels and risk of dementia in those without diabetes.

2,067 older men and women free of dementia and diabetes, were recruited from Group Health Cooperative, which is a health care system in Washington State. Over 7 years of follow up, blood glucose was measured repeatedly with a fasting blood glucose test.  Risk of dementia was measured by means of the Cognitive Abilities Screening Instrument. By the end of follow up, researchers had collected 35,264 measures of blood glucose in these subjects. The association between glucose levels and incidence of dementia were calculated.

By the end of follow-up, there were 524 new cases of dementia in this cohort.  Blood glucose levels were linearly and significantly associated with an increased risk of dementia, starting at fasting concentrations of 105 mg/dl. Following are the increases in risk of dementia with the corresponding average blood glucose readings:

105 mg/dl: 10% increased risk of dementia
110 mg/dl: 15% increased risk of dementia
115 mg/dl: 18% increased risk of dementia
It is also important to note that those with an average glucose reading of 95 had a 14% reduced risk of dementia.

Previous research has shown that diabetics have an increased risk of dementia.  Therefore, it is known that very high levels of blood glucose have a negative impact on the aging brain. This is the first study to show significant increases in risk of dementia with blood glucose levels well below that of diabetics.  

A fasting blood glucose reading below 100 is considered normal.  A fasting blood glucose above 125 is considered definitive for a diagnosis of diabetes.  If you fall in between (101-125) you are considered pre-diabetic.  This study showed that even a tiny increase in fasting blood glucose above normal will increase risk of dementia.  This is frightening because a huge number of American fall into this prediabetic category.  The authors felt that the increased risk of dementia was due to acute and chronic hyperglycemia, insulin resistance, and microvascular disease of the central nervous system.

Take Home Message
This is a really well designed study published in the #1 journal that will initiate more research in this area.  In the meantime, do your best to keep your fasting blood glucose levels in the normal range (even a bit lower as those with a reading of 95 mg/dl had a reduced risk of dementia). The best way to do this is to exercise daily, keep your weight in a healthy range, and eat a low glycemic load diet.

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