The Diabetes Connection to Alzheimer's Disease and Dementia

By now, most of us know that diabetes can lead to a series of other health problems and life-threatening conditions. Too much sugar in the blood left unchecked over time can cause harm to your kidneys, nerves, blood pressure, eyes, skin, and can lead to a heart attack or stroke.

During World Diabetes Month, I dedicated one of my blogs to the growing trend of diabetes-related kidney failure, and just recently addressed liver failure caused by diabetes.

It is now high time to discuss the many common threads between diabetes and Alzheimer's, vascular dementia, and other forms of dementia.[i]

Several studies have indicated that people with diabetes are twice as likely to develop Alzheimer's.

  • Estimates from 2015 report 40% of Alzheimer's cases were connected to both diabetes AND pre-diabetes.ii] 
  • With global projections indicating a 54% spike in adults with diabetes by the year 2030, the potential for Alzheimer's and dementia cases to rise in a direct relationship is very realistic.

In recent years, these studies have shown the link between diabetes and Alzheimer's disease to be so strong that many have suggested a more fitting name for this disease that deteriorates memory and other brain functions – Type 3 Diabetes.

We know that diabetes occurs when the body cannot produce enough insulin (or use the insulin it makes correctly) to control sugar levels (or glucose) in the blood. 

iStock-469723628 memory loss conceptGlucose is one of the primary sources of fuel that the body needs to provide energy to perform all necessary functions. Accordingly, research has proven that glucose is not used correctly in the brains of people with Alzheimer's, quite possibly due to the death of nerve cells that send messages to the brain. Vascular dementia, for example, is caused by a lack of oxygen that kills brain cells, which would typically communicate with each other.[iii] 

Therefore many scientists refer to Alzheimer's and dementia as the "diabetes of the brain" because of how this category of the disease affects the ability of glucose in the brain to "do its job."

Case studies have also established that type 2 can be a significant risk factor for Alzheimer's and most forms of dementia because they both share the same cardiovascular problems – obesity, heart disease (familial and otherwise), high cholesterol, high blood pressure, damaged blood vessels, and circulation issues.[iv]

Another interesting factor is that our bodies have an insulin-degrading enzyme (IDE) that breaks down insulin to ensure that blood glucose levels do not drop too low. This same IDE also helps to destroy Alzheimer's plaques in the brain. If the IDE is too busy attacking excessive insulin levels in the brain (that are the result of too much sugar consumption from a poor diet), it cannot effectively fight the buildup of plaque, thus causing Alzheimer's.[v]

iStock-482546476 colorful abstract brain illustrationA 2013 study published in the July issue of Alzheimer’s & Dementia that same year was the first to demonstrate that people recently diagnosed with type 2 diabetes also had signs of brain dysfunction. The participants in the study showed elevated levels of insulin resistance in the brain and a reduced ability to use glucose to fuel normal brain function.[vi] 

In addition to the common characteristics involving insulin resistance, another critical factor is age. Alzheimer's and diabetes are the two most common diseases of aging. 12% of all adults aged 65 and over have Alzheimer's, while 26% of the 30 million Americans with diabetes are in this same age group.[vii] 

Aging is a crucial factor to me as I feel that many physicians write-off type 2 as "part of aging" and are seemingly cavalier about care management. This gap in care for the elderly will be a topic of one of my upcoming blogs!

The silver lining for this health dilemma is that the same recommended strategies for managing or preventing diabetes also apply to Alzheimer's.

  • Cut added sugars out of your diet, and while you are at it, commit to eating healthier food that is nutrient-rich, as well as LDL carbs with "good fat" HDL carbs. Consider the Mediterranean Diet!
  • Exercise regularly.
  • Don’t smoke or quit smoking (NOW!) and curb your alcohol intake.
  • Give your brain a regular workout, too. While this applies primarily to Alzheimer’s, the commitment to reading more and playing brain teaser/memory games will also stimulate you to be more active physically.

Finally, while the research is new, diabetes experts feel that insulin and other diabetes drugs could be re-purposed for Alzheimer's, especially those designed for intranasal delivery (as opposed to injections). In the meantime, we should all be committed to the tips mentioned above to prevent both life-threatening diseases.

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Sean Browne

Sean Browne

Former Chief Revenue Officer, CCS Medical

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