When we think about diabetes, we tend to think about blood sugar, diet and physical health. When we think about Alzheimer’s disease or dementia, we think about memory and the brain. But growing research is showing that these areas of health may be more closely connected than many people realise.
Scientists have been studying the relationship between metabolic health, insulin resistance and Alzheimer’s disease for a number of years. You may even have come across the term “type 3 diabetes” being used to describe Alzheimer’s disease. But is Alzheimer’s really another form of diabetes?
The answer is more complicated. Alzheimer’s disease is not officially recognised as “type 3 diabetes”, and diabetes does not mean that someone will develop dementia. However, there is credible evidence linking diabetes, insulin resistance and metabolic health with dementia risk.
Understanding that connection may give us another reason to take our overall health, including our metabolic health, seriously throughout life.
What Does Insulin Have to Do With the Brain?
Insulin is best known as the hormone that helps regulate blood glucose, but its role isn’t limited to the rest of the body. Insulin signalling also takes place within the brain, where it is involved in processes including energy metabolism and healthy neuronal function.
The brain itself is remarkably energy-demanding. When the way it uses glucose and responds to insulin becomes disrupted, researchers believe this may contribute to changes associated with cognitive decline.
Studies investigating Alzheimer’s disease have identified disturbances in brain glucose metabolism and insulin signalling. Researchers are continuing to investigate how these changes interact with other features of Alzheimer’s disease, including inflammation and the accumulation of amyloid and tau proteins.
Importantly, this does not mean that insulin resistance alone causes Alzheimer’s disease. Alzheimer’s is a complex neurological disease involving numerous biological, genetic, environmental and lifestyle factors.
Why Do People Call Alzheimer’s “Type 3 Diabetes”?
The phrase has gained considerable attention online, but it actually originated from scientific research into the relationship between Alzheimer’s disease and insulin resistance in the brain. Researchers have sometimes used “type 3 diabetes” as a way of describing the hypothesis that impaired insulin signalling and glucose metabolism within the brain may play a role in Alzheimer’s disease.
A large systematic review published in 2025 examined more than 200 peer-reviewed studies and found significant evidence connecting insulin resistance and disrupted glucose metabolism with processes involved in Alzheimer’s disease.
However, “type 3 diabetes” remains a research concept. It is not an officially recognised medical diagnosis, and Alzheimer’s disease should not simply be described as another form of diabetes. That distinction is important, particularly when health information is shared on social media.
Diabetes Is a Recognised Dementia Risk Factor
What is much more firmly established is the relationship between diabetes and dementia risk. Research has consistently found that people with type 2 diabetes have an increased risk of developing dementia compared with people who do not have diabetes. There are several possible explanations.
Diabetes frequently occurs alongside other conditions associated with dementia risk, including high blood pressure, high cholesterol and obesity. Diabetes can also affect blood vessels, including those supplying the brain, while insulin resistance itself is being investigated for its potential role in Alzheimer’s-related changes. Having diabetes certainly does not mean that a person will develop dementia. It means that diabetes is one of several factors associated with an increased risk.
The Latest WHO Guidance Puts Metabolic Health in the Spotlight
This connection has become particularly relevant following the World Health Organization’s updated guidelines on reducing the risk of cognitive decline and dementia, released in 2026. According to the WHO, up to 45% of dementia risk may be attributable to potentially modifiable factors.
These include:
• Diabetes
• High blood pressure
• High cholesterol
• Physical inactivity
• Tobacco use
• Harmful alcohol use
• Social isolation
• Air pollution
The WHO recommends managing cardiometabolic conditions such as diabetes, hypertension and high cholesterol as part of a broader approach to reducing dementia risk.
Other recommendations include regular physical activity, following a healthy diet, remaining socially and cognitively active, stopping tobacco use and reducing harmful alcohol consumption.
The important message is not that dementia can always be prevented. It cannot. Instead, it is that looking after our overall health throughout life may also help us look after our brain health.
There Is No Single “Anti-Alzheimer’s” Diet or Supplement
The growing interest in metabolic health can unfortunately also lead to claims that certain diets, supplements or products can prevent or reverse Alzheimer’s disease. Current evidence does not support such simple solutions.
In fact, the WHO’s updated guidelines do not recommend taking omega-3 supplements, vitamins B or E, or multivitamin and mineral supplements specifically to reduce dementia risk when there is no diagnosed deficiency. Instead, the evidence points towards looking at health as a whole: staying physically active, eating a balanced diet, managing existing medical conditions, maintaining social connections and seeking appropriate medical care.
Anyone living with diabetes or concerned about their metabolic health should speak to their doctor or healthcare professional rather than making significant changes to medication or treatment based on information seen online.
Looking at the Whole Person at Protea Memory Clinic
At Protea Memory Clinic, we know that dementia is rarely experienced in isolation. People living with dementia may also be managing diabetes, cardiovascular conditions, mobility difficulties and other age-related health concerns. This is why personalised care and collaboration with families, doctors and other healthcare professionals are so important.
Our approach considers the whole person, from their physical and medical needs to their emotional well-being, daily routines, nutrition, social interaction and quality of life.
We also believe that families should have access to reliable information about dementia. New research can be incredibly encouraging, but it can also be confusing, particularly when complex scientific findings are reduced to dramatic headlines or social media posts.
The Bigger Message: What’s Good for the Body Can Be Good for the Brain
Calling Alzheimer’s disease “type 3 diabetes” oversimplifies a very complex disease.
But behind the phrase is an important area of research. Our metabolic health and brain health are connected, and conditions such as diabetes are now recognised as part of the wider picture of dementia risk.
We cannot control every factor that influences whether someone develops dementia. Age, genetics and many other factors are beyond our control. But the growing evidence around modifiable risk factors gives us something valuable: practical areas of health that we can pay attention to throughout life.
Taking care of the heart, managing blood pressure, cholesterol and diabetes, staying active, eating well and remaining socially connected aren’t guarantees against dementia.
They are, however, worthwhile investments in both our physical and brain health. At Protea Memory Clinic, our focus remains on providing compassionate, specialised dementia care while helping residents and their families navigate the condition with credible information, personalised support and a better understanding of the journey ahead.
References
World Health Organization (2026). Risk reduction of cognitive decline and dementia: WHO guidelines, second edition.
WHO – Risk Reduction of Cognitive Decline and Dementia
World Health Organization (2026). New WHO guidelines: up to 45% of dementia risk could be prevented or delayed.
WHO – New Dementia Risk Reduction Guidelines
Alzheimer’s Society. Diabetes and the risk of dementia.
Alzheimer’s Society – Diabetes and Dementia Risk
Atabi, F., et al. (2025). A systematic review on type 3 diabetes: bridging the gap between metabolic dysfunction and Alzheimer’s disease. Diabetology & Metabolic Syndrome, 17, 356. This is the particularly useful source for explaining where the term “type 3 diabetes” comes from and why it shouldn’t be treated as an official diagnosis.
Read the full study – PubMed
Lourenço, L.G.C., et al. (2024). Brain insulin resistance and Alzheimer’s disease: a systematic review. This reviews the evidence around insulin resistance within the brain and Alzheimer’s disease.
Read the full study – PubMed Central
Soltani, S., et al. (2025). Relationships Between Brain Glucose Metabolism Patterns and Impaired Glycemic Status: A Systematic Review of FDG-PET Studies With a Focus on Alzheimer’s Disease. Human Brain Mapping, 46(4), e70180. The review included 23 studies and found that 22 reported associations between hyperglycaemia or insulin resistance and reduced brain glucose metabolism.
Read the study – PubMed
