Diabetes is a chronic health problem affecting millions of people globally. It means that the body does not produce enough insulin or cannot use it properly. Insulin is a hormone that the body needs to convert glucose from food into energy.

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Diabetes can lead to serious health problems, including dementia. In fact, people with diabetes are nearly twice as likely to develop dementia as those without the disease. Experts do not currently understand why this is, but they are studying how the two conditions are connected.

This article examines the link between diabetes and dementia and explains how people can manage these chronic health conditions.

More than 37 million people in the United States are living with diabetes. This equates to about 11.3% of the U.S. population. This total is based on 28.7 million confirmed diagnoses and an estimated 8.5 million people living with the condition who remain undiagnosed.

The global diabetes prevalence in 2019 was 9.3%, or 463 million people. Experts expect it to rise to 10.2%, or 578 million people, by 2030.

There is a link between diabetes and dementia. People with type 2 diabetes are more likely to experience cognitive impairment, including Alzheimer’s disease and vascular dementia.

Cognitive impairment refers to various issues, such as trouble concentrating, learning new things, remembering information, and making decisions.

A 2021 study looked at the link between a person’s age at the onset of diabetes and the development of dementia. The researchers recruited 10,308 people aged 35–55 years in 1985–1988. They recorded 1,710 cases of diabetes and 639 cases of dementia.

The authors write that the rate of dementia at age 70 was 8.9 per 1,000 participants assessed annually, in those without diabetes.

In comparison, the rate among those with diabetes was:

  • 10.0 for those with onset up to 5 years earlier
  • 13.0 for those with onset 6–10 years earlier
  • 18.3 for those with onset more than 10 years earlier

In other words, the younger someone is when they develop diabetes, the higher their risk of developing dementia.

There are various theories to how type 2 diabetes could lead to dementia:

  • Diabetes affects the heart. Heart disease and increased blood pressure can increase the risk of stroke, which can lead to dementia. However, strokes alone do not fully explain the association, as some research shows that diabetes can increase the risk of dementia without a history of stroke.
  • Chronic diabetes leads to the narrowing of the small arteries and capillaries that deliver fresh oxygen and nutrition throughout the body, including the brain. Together with high blood pressure and elevated lipids — both of which are common in people with diabetes — this can lead to cerebrovascular damage, which might increase the risk of vascular dementia.
  • Hypoglycemia or low blood sugar may contribute. Controlling blood sugar typically reduces the long-term risks of heart disease and stroke, but it may also lead to memory loss and dementia. A potential reason is that low blood sugar damages the hippocampus, which plays a role in memory.
  • Another theory is that diabetes directly causes Alzheimer’s disease. It seems that insulin plays a critical role in forming amyloid plaques. Research suggests that high blood sugar levels can lead to an increase in beta-amyloid, a protein that occurs naturally in the brain. Beta-amyloid is a sticky substance, and abnormal levels can lead to it forming clumps or plaques. These plaques are a hallmark of Alzheimer’s disease.

Diabetes and dementia are both complex conditions, meaning that various factors can affect someone’s life expectancy. For example, someone with diabetes who does not manage their glucose levels properly or care for themselves will likely have a shorter life expectancy than someone with well-managed diabetes.

People with diabetes and dementia often have other chronic conditions that can further complicate their health.

Having both conditions appears to shorten life expectancy. A 2019 study linked diabetes with a higher dementia and mortality risk. During the 12-year follow-up of 8,328 participants, the researchers associated diabetes with an increased risk of dementia and a lower dementia-free life expectancy. Dementia-free life expectancy for a 70-year-old with diabetes was 13.4 years for females and 16.1 years for males. Among those without the condition, the results were 16.5 years and 19.6 years for females and males, respectively.

Diabetes symptoms include:

The symptoms of dementia may include:

  • memory problems, especially forgetting recently learned information
  • confusion and disorientation
  • difficulty with planning or solving problems
  • trouble with words and understanding what people are saying
  • vision problems
  • changes in mood or behavior
  • misplacing things
  • poor judgment

People living with diabetes and dementia require special care and management. Therefore, working with a doctor to develop a comprehensive treatment plan is important.

There is no one-size-fits-all approach to managing diabetes and dementia. However, caregivers must understand the impact of dementia on a person’s understanding of their diabetes. The individual may not undertake self-care tasks, such as managing their medication and monitoring their blood glucose levels.

Moreover, individuals with dementia have a higher risk of hypoglycemia than other people. They may also be at risk of drug interactions and adverse reactions due to taking multiple medications.

The primary management approach involves helping the individual be as independent as possible. This may include motivational interventions or educational programs. Although this is appropriate in the earlier stages of dementia, a person will become less able to care for themselves as dementia progresses, and interventions may instead have to focus on caregivers.

People can adjust their lifestyle to reduce their risk of developing type 2 diabetes. Depending on their current lifestyle, the steps to take may include:

  • Losing weight: For people with excess body weight, losing 5–7% of their weight may reduce the risk of diabetes.
  • Moving more: It is important to aim for a minimum of 30 minutes of physical activity 5 days a week.
  • Eating a nutritious diet: A well-balanced diet should focus on whole grains, fruits, vegetables, and lean protein. It is best to limit the intake of sugary drinks and processed foods.
  • Stopping smoking: People who smoke are 30–40% more likely to develop type 2 diabetes than those who do not.

There are currently no proven approaches that can treat or prevent Alzheimer’s disease and related dementias. However, taking the steps above, if applicable, may help.

Diabetes and dementia are two conditions that may co-occur. Diabetes appears to increase the risk of dementia. This may be because insulin contributes to amyloid plaque formation in the brain, a hallmark of Alzheimer’s disease.

Managing diabetes and dementia can be complex. There is no one-size-fits-all approach, but working with a doctor to develop a comprehensive treatment plan is important. Creating a supportive environment for the individual and their caregivers is also crucial.

A person can reduce their risk of diabetes by following a healthy lifestyle. However, there are no proven ways to prevent dementia.