Two studies referred to in Clinical Endocrinology News, Sept. 2013, refer to studies of older adults with high blood glucose and/or diabetes and analyzing the associated risk for dementia. One study, in JAMA Neurology, suggests there is no association with “serial measures of glucose and insulin homeostasis taken over 20 years show no association with the development of Alzheimer’s disease symptoms or pathology.” However, the study followed 197 participants which is a rather small sample size. The participants had “at least two oral glucose tolerance tests performed during follow up, and “53 underwent brain imaging. All went through brain autopsies.” This study also used data from the Baltimore Longitudinal Study of Aging and not from their own study design.
The second study, found in NEJM, stated “higher glucose levels were associated with an elevated risk of dementia in a community-based cohort study.” This study had 2067 participants who were followed every 2 years, median follow-up period of 6.8 years, and underwent numerous glucose tests (10,208), beginning in the 1990’s. Those with an average blood glucose of 115mg% versus 100mg% in the preceding 5 years had a hazard ratio of 1.18 for risk of dementia. The data in this study appear to be more rigorous and show a link between high blood glucose and dementia.
Regardless, there appears to be a need for more research in this area in order to determine the significance of the link, if any, in order to best develop guidelines in the prevention of dementia. Lastly, since many older adults have no control over whether they develop diabetes, it stands to reason that good control of blood glucose is in their best interest and may reduce the risk for deleterious effects on the brain. However, it should be noted that those with diabetes and history of hypoglycemia are also at increased risk for cognitive impairment and worsening memory health issues.