You may have heard that diabetes and Alzheimer’s disease are linked. This connection can sound concerning, especially if you are living with diabetes. But understanding what the research shows can help separate facts from myths, and help you focus on what supports long‑term health. Credentialled Diabetes Educator and Registered Nurse, Carolien Koreneff, explains.

What is Alzheimer’s disease?

Alzheimer’s disease is a condition that affects the brain. It causes problems with memory, thinking, language, and daily activities. These changes usually develop slowly and become more noticeable over time.

Alzheimer’s disease is the most common cause of dementia. It is not a normal part of ageing, although increasing age is a major risk factor.

How is diabetes linked with Alzheimer’s disease?

Research has consistently shown that people living with type 2 diabetes have a higher risk of developing Alzheimer’s disease compared with people who do not have diabetes. One of the main reasons is insulin resistance.

Insulin is a hormone that helps glucose (sugar) move from the bloodstream into the body’s cells so it can be used for energy. This includes brain cells.

In type 2 diabetes, the body becomes less sensitive to insulin, this is more commonly referred to as insulin resistance. Research suggests that similar insulin resistance can also occur in the brain.

When brain cells do not respond well to insulin:

• Less glucose can enter brain cells
• Brain cells may struggle to get the energy they need
• Over time, this can affect memory, reasoning, and judgement

What is “type 3 diabetes”?

You may see Alzheimer’s disease described as “type 3 diabetes”. This term is sometimes used in research to describe insulin resistance in the brain and its possible role in Alzheimer’s disease.

It is important to be clear that:

• “Type 3 diabetes” is not an official medical diagnosis
• It is not recognised as a form of diabetes
• The term is used mainly in research settings, not in clinical care

Diabetes Australia cautions against using this term outside of research because it can be confusing and misleading for people living with diabetes.

Does having diabetes mean you will get Alzheimer’s disease?

No. Having diabetes does not mean you will develop Alzheimer’s disease.

While studies suggest that people with type 2 diabetes have a 50–65% higher risk of developing Alzheimer’s disease, many people with diabetes never develop dementia.

Alzheimer’s disease also occurs in people who do not have diabetes. The risk is influenced by many factors, including:

• Age
• Genetics
• Cardiovascular health
• Physical activity levels
• Education and lifelong learning

Diabetes is just one risk factor among many, not a direct cause.

Why glucose management matters for brain health

The brain is a very energy‑dependent organ. Even though it makes up only around 2% of body weight, it uses about 20% of the body’s glucose supply to support thinking, memory, attention, and decision‑making.

Very high or very low blood glucose levels can affect brain function in the short term, leading to:

• Difficulty concentrating
• Slower thinking
• Confusion or fatigue

Over many years, long‑term high glucose can also damage blood vessels, including those supplying the brain, which may increase the risk of cognitive decline.

What supports brain health for people with diabetes?

The encouraging news is that many actions that support diabetes management also support brain health.

Physical activity

Regular physical activity:

• Improves insulin sensitivity throughout the body and brain
• Increases blood flow to the brain
• Supports the formation and maintenance of brain connections

Research suggests regular exercise can reduce the risk of developing Alzheimer’s disease by up to 50% and may slow progression when cognitive changes are already present.

Glucose management

Keeping glucose levels within your individual target range, as much as possible, helps protect blood vessels, nerves and brain function.

Targets should always be personalised and discussed with your health care team.

Heart and vascular health

High blood pressure, high cholesterol levels, and smoking all increase the risk of both diabetes complications and dementia. Managing these factors supports both heart and brain health.

Mental and social engagement

Staying socially connected and mentally active through learning, conversation, hobbies, and problem‑solving helps build brain resilience and supports cognitive health.

A supportive message

Hearing about a link between diabetes and Alzheimer’s disease can be worrying. It is important to remember:

• Diabetes is manageable
• Risk is not fixed
• Lifestyle and medical care make a real difference

If you notice changes in memory or thinking, or if you are concerned about brain health, speak with your GP, diabetes educator, or health care team. Early conversations can lead to reassurance, support, and practical strategies.

Key take‑home points

• Alzheimer’s disease is linked to insulin resistance in the brain, not just ageing
• “Type 3 diabetes” is a research term, not a diagnosis
• Diabetes increases risk but does not make Alzheimer’s disease inevitable
• Physical activity, glucose management, and cardiovascular health support brain health