Diabetes and Dementia: Can Diabetes Lead to Alzheimer’s Disease?

Numerous studies have shown a connection between diabetes and dementia. The connection is significant. Your Brain Matters (n.d.) reports that diabetes increases the risk of any type of dementia by 47 percent and of Alzheimer’s disease specifically by 39 percent. Diabetes increases the risk of vascular dementia by a whopping 138 percent. Another report asserts that diabetes increases dementia risk in general by 100 percent (Colino, 2017). While other groups and studies have reported slightly different numbers, the pattern is evident: diabetes can contribute to dementia in general and Alzheimer’s in particular.

That diabetes, and even prediabetes, are risk factors for cognitive decline, impairment and dementia has been established. Also, known is that diabetes and its problems with blood sugar, insulin, blood vessel damage, and nerve damage contribute to the development of brain diseases. What isn’t fully understood is exactly how diabetes can change the brain.

Researchers continue to study the connection between dementia and diabetes, so our knowledge will continue to grow. Here’s a look at what is known so far, because when you know about the connection, you can take measures to prevent it in yourself or a loved one.

Diabetes and Dementia: What is Dementia, and is there a Type 3 Diabetes?

Dementia is a general term for a group of symptoms and experiences. Dementia in general involves:

• Memory loss
• Difficulty with problem-solving
• Confusion/thinking problems
• Problems with language usage

Dementia can range from mild to severe and involve minor disruptions to daily life to serious disability. Forms of dementia include mild cognitive impairment, vascular dementia (brain damage due to reduced blood flow to the brain, possibly caused by blood vessel damage from high blood sugar), other forms of dementia, and Alzheimer’s disease.

Alzheimer’s disease is a brain disease that worsens over time ("Alzheimer's Disease: Prognosis and Complications"). It severely impedes memory, learning, reasoning, communication, and the ability to complete ordinary daily tasks. Alzheimer’s can even cause changes in personality or behavior and often leads to increased anxiety, agitation, paranoia, and delusions.

Type 2 diabetes is a risk factor for dementia, including Alzheimer’s. Of course, not everyone with diabetes will develop dementia, and not every person with Alzheimer’s has type 2 diabetes. The connection between these diseases, however, is significant enough that Alzheimer’s is sometimes called Type 3 diabetes or even brain diabetes. Type 3 diabetes isn’t an actual type of diabetes. It refers to the contribution diabetes makes to Alzheimer’s disease.

What is the Link Between Diabetes and Dementia?

Diabetes is a disease in which the glucose (sugar) created during digestion can’t get out of the bloodstream and into the cells as it should. Glucose is a source of energy for the body and is the brain’s primary energy source. In diabetes, blood sugar can be too high at times and too low at others. This fluctuation between unhealthy extremes can lead to brain damage.

Many aspects of diabetes can damage the brain enough to lead to dementia:

• Hyperglycemia (high blood sugar)
• Hypoglycemia (low blood sugar)
• Improper use of glucose
• Blood vessel damage that reduces blood flow, starving brain of energy, oxygen, and nutrients
• Excess insulin that leads to changes in brain chemistry
• Chronic inflammation due to hyperglycemia

Additionally, studies have shown that type 2 diabetes might lead to the build-up of toxic proteins in the brain. Diabetes seems to contribute to dementia in part by impairing the brain’s ability to remove waste products. Diabetes also interferes in the creation of new connections between brain cells.  

It’s clear that insulin, glucose, blood vessel damage, and inflammation in diabetes contributes to dementia. However, brain damage isn’t guaranteed. If you live with diabetes or prediabetes, you’re not doomed to dementia.

Lower Your Risk of Both Dementia and Diabetes

You don’t have to passively wait and hope that diabetes doesn’t cause dementia. There are many factors in your control that you can take charge of. The actions that reduce the risk of diabetes and improve the effects of the disease are the same actions that lower your risk of dementia and Alzheimer’s.

• Be intentional about what you eat. Avoid processed, sugary foods and get plenty of whole grains, fruits, vegetables, and protein
• Increase your physical activity. Exercise most days of the week, and do something you enjoy.
• Maintain a healthy weight
• Don’t smoke
• Limit alcohol
• Keep regular appointments with your doctor and diabetes care team
• Take prescribed medications

You don’t have to make major changes all at once in order to improve your health. Identify small steps to begin, do them regularly, and gradually add more. These lifestyle changes can improve diabetes and help prevent dementia, including Alzheimer’s disease.

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