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How Diabetes Is Connected to Alzheimer's Disease


Jennifer Larson

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Questions This Article Answers:

  • What are the key indicators of Alzheimer’s disease in the brain?
  • How is type 2 diabetes linked to symptoms of Alzheimer’s?
  • If I’m diabetic, how can I reduce my risk of Alzheimer’s?

Diabetes is linked to a number of other serious health conditions, including heart disease, high cholesterol, high blood pressure, and stroke. Even if you keep your blood sugar levels under control, you’re still at increased risk for cardiovascular disease, according to the American Heart Association. 

If that’s not enough, add one more serious health condition to the list. Research shows people with diabetes are already more likely to develop dementia than people without diabetes—and they’re at increased risk for developing Alzheimer’s disease.

How Alzheimer’s Disease Develops in the Brain

Two hallmarks of Alzheimer’s disease are large amounts of plaques and tangles in the brain. The plaques are waste piles of protein called beta-amyloid that accumulate in the brain. Those beta-amyloid proteins tend to stick together, forming plaques that can build up and block the brain cells’ ability to communicate with each other. However, even small clumps of the protein seem to be problematic, according to the Alzheimer’s Association, because they can block that important signaling between cells. 

Meanwhile, tangles are twisted strands of a protein called tau. Experts believe these tangles and plaques lead to cell death, which eventually results in dementia.

The Link Between Alzheimer’s Disease and Diabetes

A strong link seems to exist between high blood glucose levels and Alzheimer’s disease, according to a recent study in the Journal of Alzheimer’s Disease. Because they often have high blood sugar levels, people with type 2 diabetes seem to be more likely to develop higher levels of that toxic beta-amyloid protein. 

The beta amyloid proteins also destroy synapses, which are the gaps or connections between neurons, before the plaques can form, according to other research. When the synapses are destroyed or eroded, the brain has trouble forming and retaining memories. That can show up as cognitive impairment, or dementia. 

People with type 2 diabetes also seem to have higher levels of the tau protein in their cerebrospinal fluid, although scientists have not yet pinpointed the exact reason. According to a recent study in the journal Neurology, the higher levels of tau protein suggests they may be more likely to develop Alzheimer’s disease because those higher levels tend to result in more tangles made up of that same protein in the brain. The tangles can impair the brain’s ability to transport nutrients and other essentials, which leads to cell death.  

How to Reduce Your Risk

Managing your diabetes appropriately is one of the most important steps you can take to potentially reduce your risk of developing dementia. If you’re not already in the habit of maintaining very good control over your blood sugar levels, it’s time to rededicate yourself to the cause. You may need to reevaluate your approach. Talk to your doctor about how often you need to test your blood sugar levels, if applicable, and discuss the medications you’re taking. 

The Alzheimer’s Association notes it may also be helpful to embrace certain lifestyle choices to help keep your brain healthy, even if there’s not yet scientific evidence to prove those choices will be 100% effective. For example, eating a healthy diet can lower your risk of heart disease, which is linked to Alzheimer’s. You might consider a Mediterranean-style diet or the DASH (Dietary Approaches to Stop Hypertension) diet. Both of these heart-healthy diets emphasize eating lots of fruits, vegetables, whole grain, and low-fat sources of protein. 

Consider boosting the amount of physical activity you’re currently getting; exercise can also reduce your risk of heart disease and stroke and contribute to your overall health. It can also help you better manage your diabetes. The Centers for Disease Control and Prevention typically recommends 150 minutes of moderately intense activity per week.

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Medical Reviewers: William C. Lloyd III, MD, FACS Last Review Date: Feb 22, 2016

© 2017 Healthgrades Operating Company, Inc. All rights reserved. May not be reproduced or reprinted without permission from Healthgrades Operating Company, Inc. Use of this information is governed by the Healthgrades User Agreement.

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Medical References

  1. Alzheimer's and Dementia Prevention: How to Reduce Your Risk and Protect Your Brain as You Age.
  2. Alzheimer Basics: Plaques and Tangles. Alzheimer’s Association.
  3. Anderson P. Type 2 Diabetes Linked to Tau Tangles in Brain. Medscape. Sept. 9, 2015.
  4. Bitel CL, et al. Amyloid-β and tau pathology of Alzheimer's disease induced by diabetes in a rabbit animal model. Journal of Alzheimers Disease. 2012;32(2):291-305.
  5. Cardiovascular Disease & Diabetes. American Heart Association.
  6. De la Monte SM and Wands JR. Alzheimer's Disease Is Type 3 Diabetes–Evidence Reviewed. Journal of Diabetes Science and Technology. 2008 Nov; 2(6): 1101–1113.
  7. Diabetes and Alzheimer's linked. Mayo Clinic.
  8. Diabetes and cognitive decline. Alzheimer’s Association.
  9. Kim B, et al. Hyperglycemia-induced tau cleavage in vitro and in vivo: a possible link between diabetes and Alzheimer's disease. Journal of Alzheimers Disease. 2013;34(3):727-39.
  10. Macauley SL, et al. Hyperglycemia modulates extracellular amyloid-β concentrations and neuronal activity in vivo. Journal of Clinical Investigation. May 4, 2015.
  11. Scientists reveal how beta-amyloid may cause Alzheimer's. Stanford Medicine.
  12. Willette AA, et al. Insulin Resistance, Brain Atrophy, and Cognitive Performance in Late Middle–Aged Adults. Diabetes Care February 2013 vol. 36 no. 2 443-449.

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