What Is the Connection Between Alzheimer’s and Diabetes?

Q. My sister is overweight, and her doctor says she is prediabetic. She is trying to become healthier and exercise more often to prevent it from becoming diabetes. She read somewhere that there is a correlation between diabetes and Alzheimer’s. I thought that it was all speculation that diabetes is somehow related to cognitive decline. Are there any new studies that prove that there is or isn’t a connection? If they are in fact connected, is there a relationship between age at diabetes onset and the risk of developing Alzheimer’s? Thanks for your help!

A. There are currently more than 34 million Americans living with diabetes. According to the American Diabetes Association, 25 percent of people age 65 and older in the United States are diabetic (diagnosed and undiagnosed), and about half are “pre-diabetic,” which is a term doctors use to describe a condition in which blood sugar is high, but not high enough to be considered Type 2 diabetes. It is important to point out that not everyone who is diagnosed as being pre-diabetic will become diabetic.

In the past, research has indicated that cognitive decline and diabetes are connected, but not a lot of information was available. Doctors and researchers were aware that high blood sugar or insulin can harm the brain in several ways:

  • Diabetes raises the risk of heart disease and stroke, which hurt the heart and blood vessels. Damaged blood vessels in the brain may contribute to cognitive decline;
  • The brain depends on many different chemicals, which may be unbalanced by too much insulin. Some of these changes may contribute to triggering cognitive decline;
  • High blood sugar causes inflammation. This may damage brain cells and cause dementia to develop.

Scientists Are Finding More Evidence That Could Link Type 2 Diabetes with Alzheimer’s

Most people with diabetes have Type 2, which is frequently linked to lack of exercise and being overweight. When diabetes is not controlled, too much sugar remains in the blood. Over time, this can damage organs, including the brain. Scientists have been finding more evidence that could link Type 2 diabetes with Alzheimer’s disease, the most common type of dementia. Several research studies following large groups over many years suggest that adults with Type 2 diabetes have a higher risk of developing Alzheimer’s. Here are some of the things that research has shown about the relationship between diabetes and cognitive decline:

  • People with Type 1 diabetes are at greater risk of dementia than people without diabetes. According to one study’s results, Type 1 diabetics were 93 percent more likely to develop dementia. A 2021 study for Kaiser Permanente Northern California showed older adults with Type 1 diabetes who were hospitalized for just one blood sugar extreme were at higher risk for dementia — and those who were hospitalized for both highs and lows were six times more likely to later develop dementia.
  • There’s a strong correlation between Alzheimer’s disease and high blood sugar levels. Researchers found that people with high blood sugar levels — such as those linked with Type 2 diabetes — had a dramatic increase in beta-amyloid protein, one of the hallmarks of Alzheimer’s disease.
  • People in the early stages of Type 2 diabetes have signs of brain dysfunction. Researchers also found that those who showed high levels of insulin resistance in the brain had a reduced ability to use glucose to fuel normal brain function.
  • Individuals with Type 2 diabetes show accelerated cognitive decline, specifically in executive function and information-processing speed. Researchers found that those whose onset of Type 2 diabetes was at a younger age are at higher risk of dementia.
  • The early effects of diabetes on the brain are related to levels of a blood protein called hemoglobin A1C (HbA1C). Researchers found that even people who had diabetes for less than 10 years had deficits in memory function typically associated with a brain region called the hippocampus. They found that people with diabetes had smaller hippocampal sizes than people without diabetes. They also discovered that the decreases in hippocampal size were correlated to HbA1C blood levels, suggesting that HbA1C could be used to indicate hippocampal function and/or the onset of memory loss.
  • The amyloid precursor protein gene, known to be involved in some cases of Alzheimer’s, affects the insulin pathway. Disruption of this pathway is a hallmark of diabetes. Researchers are optimistic that the research could point to a therapeutic target for both diseases.

Additional New Research Examines Relationship Between Age at Diabetes Onset and the Risk of Developing Dementia

Another newly-published study examined the association between age of onset of diabetes and the development of dementia. The study involved 10,308 individuals who were aged 35 to 55 years at the beginning of the study in the mid-late 1980s. Data on diabetes exposure, including fasting glucose and the “Finnish Diabetes Risk Score,” were obtained at ages 55, 60, 65, and 70. (The Finnish Diabetes Risk Score includes age, family history of diabetes, personal history of elevated blood glucose, fruit and vegetable consumption, blood pressure medication, physical activity, body mass index, and measured waist circumference.)

Dementia due to any cause was the primary outcome measure. In addition to diabetes, researchers also examined the effects of age, sex, race, smoking, alcohol consumption, physical activity, fruit and vegetable consumption, high blood pressure, body mass index, coronary heart disease, heart failure, stroke, medications, and the Alzheimer’s risk factor gene, apolipoprotein E.

  • 1,710 cases of diabetes and 639 cases of dementia were recorded.
  • For every 1,000 people examined yearly, the rates of dementia were 8.9 percent in those without diabetes at age 70. Comparable rates of dementia for those with diabetes were 10 percent for those with onset up to five years earlier, 13 percent for six to 10 years earlier, and 18.3 percent for more than 10 years earlier.
  • These results seem to indicate that the earlier you develop diabetes, the greater your risk is for developing dementia.

Alzheimer’s Has Been Called “Type 3 Diabetes”

Alzheimer’s disease has even been called “type 3 diabetes” because of shared molecular and cellular features among diabetes and Alzheimer’s. According to Harvard Health, “insulin plays a critical role in the formation of amyloid plaques, and insulin is also involved in the phosphorylation of tau, which leads to neurofibrillary tangles. In other words, whereas insulin resistance in the body can lead to Type 2 diabetes, insulin resistance in the brain can lead to the plaques and tangles of Alzheimer’s disease.”

Reducing Risk for Diabetes

Due to increasing rates of obesity, inactivity, and an aging population, diabetes is more prevalent than ever before. It has been known for many years that diabetes increases your risk for strokes and heart disease, and now you see that there is also a risk for Alzheimer’s and other forms of dementia.

The American Heart Association has identified lifestyle changes to achieve better cardiovascular health and reduce the risk for diabetes and dementia, as follows:

  1. Manage blood pressure;
  2. Control cholesterol;
  3. Reduce blood sugar;
  4. Get active — be physically active every day;
  5. Eat better — enjoy a healthy, low-fat diet, or perhaps a Mediterranean-style menu of foods;
  6. Maintain a healthy body weight;
  7. Treat high blood pressure;
  8. Stop smoking.

Lastly, social activities, a positive attitude, learning new things, and music can all help your brain work at its best and reduce your risk of dementia.

Speak with your doctor about whether the lifestyle modifications listed above would be right for you.

Medicaid Asset Protection

Do you have a loved one who is suffering from Alzheimer’s or another form of dementia? Persons with Alzheimer’s and their families face special legal and financial needs. At the Farr Law Firm, we are dedicated to easing the financial and emotional burden on those suffering from dementia and their loved ones. We help protect the family’s hard-earned assets while maintaining your loved one’s comfort, dignity, and quality of life by ensuring eligibility for critical government benefits such as Medicaid and Veterans Aid and Attendance. Please call us as soon as possible to make an appointment for an initial consultation:

Fairfax Alzheimer’s Planning: 703-691-1888

Fredericksburg Alzheimer’s Planning: 540-479-1435

Rockville Alzheimer’s Planning: 301-519-8041

DC Alzheimer’s Planning: 202-587-2797

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About Evan H Farr, CELA, CAP

Evan H. Farr is a 4-time Best-Selling author in the field of Elder Law and Estate Planning. In addition to being one of approximately 500 Certified Elder Law Attorneys in the Country, Evan is one of approximately 100 members of the Council of Advanced Practitioners of the National Academy of Elder Law Attorneys and is a Charter Member of the Academy of Special Needs Planners.