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Is High Blood Sugar Damaging Your Brain?

Is High Blood Sugar Damaging Your Brain?

Did you know that diabetes is a risk factor for dementia and cognitive decline? But effectively managing diabetes could actually improve long-term brain health.

In diabetes, blood glucose levels remain too high, either because the body does not make or becomes resistant to insulin. Over time, high glucose levels can have serious repercussions, such as heart disease and stroke. But lower them too much and you could face immediate and severe side effects including confusion and cognitive impairment and, possibly, an increased risk of long-term cognitive decline [1][2].

WHAT THE EVIDENCE SAYS
Diabetics have up to 73% increased risk of dementia and a 100% higher risk of developing vascular dementia than non-diabetics [3][4–6]. The association between diabetes and dementia risk is even stronger in people with the APOE4 gene [5]. Diabetes can lead to subtle cognitive decline and, in patients with mild cognitive impairment ?, it increases the odds of progressing to dementia [7–9]. The side effects of diabetes can worsen confusion and cognitive impairment in people with dementia.

Type 2 diabetes and Alzheimer's disease share certain characteristics, including impaired insulin signaling and oxidative stress [10]. Because of this, research is underway to evaluate whether some specific diabetes drugs including metformin [11], liraglutide [12], exenatide [13], and pioglitazone [14] can prevent or treat dementia even in patients without diabetes [7].

WHAT YOU CAN DO
Strong research from multiple meta-analyses indicates that preventing or effectively managing diabetes is one of the most important things you can do to reduce dementia risk and protect your brain from cognitive decline [3][15-17]. Healthy diet, exercise, and weight control are the first steps of diabetes management [10]. Older adults with diabetes who are unable to exercise at the recommended levels benefit from even modest increases in physical activity [18].

For many patients, oral or injectable prescription drugs are often required to keep blood glucose levels in the target range. Such drugs are generally safe, but some side effects and drug interactions can occur [19]. A consensus guideline for treating diabetes in older adults suggests that treatments should be simplified as much as possible [18]. For diabetics with dementia, experts recommend less stringent targets for managing blood glucose [20]. It's possible that the choice of drugs to manage diabetes can influence cognitive function or dementia risk, but more research is needed [21].

 

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  2. Ojo O, Brooke J (2015) Evaluating the Association between Diabetes, Cognitive Decline and Dementia. Int J Environ Res Public Health 12, 8281-8294.
  3. Deckers K, van Boxtel MP, Schiepers OJ et al. (2015) Target risk factors for dementia prevention: a systematic review and Delphi consensus study on the evidence from observational studies. Int J Geriatr Psychiatry 30, 234-246.
  4. Gudala K, Bansal D, Schifano F et al. (2013) Diabetes mellitus and risk of dementia: A meta-analysis of prospective observational studies. J Diabetes Investig 4, 640-650.
  5. Vagelatos NT, Eslick GD (2013) Type 2 diabetes as a risk factor for Alzheimer's disease: the confounders, interactions, and neuropathology associated with this relationship. Epidemiol Rev 35, 152-160.
  6. Chatterjee S, Peters SA, Woodward M et al. (2016) Type 2 Diabetes as a Risk Factor for Dementia in Women Compared With Men: A Pooled Analysis of 2.3 Million People Comprising More Than 100,000 Cases of Dementia. Diabetes Care 39, 300-307.
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  9. Li J, Wang YJ, Zhang M et al. (2011) Vascular risk factors promote conversion from mild cognitive impairment to Alzheimer disease. Neurology 76, 1485-1491.
  10. Sebastiao I, Candeias E, Santos MS et al. (2014) Insulin as a Bridge between Type 2 Diabetes and Alzheimer Disease - How Anti-Diabetics Could be a Solution for Dementia. Front Endocrinol (Lausanne) 5, 110.
  11. Arnold SE Effect of Insulin Sensitizer Metformin on AD Biomarkers. ClinicalTrialsgov.
  12. Edison P Evaluating Liraglutide in Alzheimer's Disease (ELAD). ClinicalTrials.gov.
  13. Kapogiannis DI A Pilot Clinical Trial of Exendin-4 in Alzheimer's Disease. ClinicalTrialsgov.
  14. Takeda Biomarker Qualification for Risk of Mild Cognitive Impairment (MCI) Due to Alzheimer's Disease (AD) and Safety and Efficacy Evaluation of Pioglitazone in Delaying Its Onset (TOMORROW). ClinicalTrials.gov.
  15. Barnes DE, Yaffe K (2011) The projected effect of risk factor reduction on Alzheimer's disease prevalence. Lancet Neurol 10, 819-828.
  16. Norton S, Matthews FE, Barnes DE et al. (2014) Potential for primary prevention of Alzheimer's disease: an analysis of population-based data. Lancet Neurol 13, 788-794.
  17. Bordier L, Doucet J, Boudet J et al. (2014) Update on cognitive decline and dementia in elderly patients with diabetes. Diabetes Metab 40, 331-337.
  18. Kirkman MS, Briscoe VJ, Clark N et al. (2012) Diabetes in older adults: a consensus report. J Am Geriatr Soc 60, 2342-2356.
  19. May M, Schindler C (2016) Clinically and pharmacologically relevant interactions of anti diabetic drugs. Ther Adv Endocrinol Metab 7, 69-83.
  20. Page A, Potter K, Clifford R et al. (2016) Medication Appropriateness Tool for Comorbid Health conditions in Dementia (MATCH-D): Consensus recommendations from a multidisciplinary expert panel. Intern Med J.
  21. Dacks PA, Armstrong JJ, Brannan SK et al. (2016) A call for comparative effectiveness research to learn whether routine clinical care decisions can protect from dementia and cognitive decline. Alzheimers Res Ther 8, 33.

Yuko Hara, PhD, is Acting Director of Aging and Alzheimer's Prevention at the Alzheimer's Drug Discovery Foundation. Dr. Hara was previously an Assistant Professor in Neuroscience at the Icahn School of Medicine at Mount Sinai, where she remains an adjunct faculty member. Her research focused on brain aging, specifically how estrogens and reproductive aging influence the aging brain's synapses and mitochondria. She earned a doctorate in neurology and neuroscience at Weill Graduate School of Medical Sciences of Cornell University and a bachelor's degree in biology from Cornell University, with additional study at Keio University in Japan. Dr. Hara has authored numerous peer-reviewed publications, including articles in PNAS and Journal of Neuroscience.

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