Blog
Type 3 Diabetes and Metabolic Health
Insulin Resistance & Cognitive Decline
Dominika Budai, MS
Physician Reviewed
Most people are familiar with Type 1 and Type 2 diabetes, but you may have recently heard the term "Type 3 diabetes." While it is not an officially recognized medical diagnosis, researchers often use this term to describe the connection between insulin resistance in the brain and cognitive decline, particularly Alzheimer's disease.
As our understanding of metabolic health grows, scientists are learning that blood sugar regulation affects much more than just weight and diabetes risk, and how it may also play a role in brain health.
What Is Type 3 Diabetes?
Type 3 diabetes is a term used to describe a theory that Alzheimer's disease may be linked to problems with insulin signaling in the brain.
Insulin is a hormone that helps cells use glucose (sugar) for energy. While most people think of insulin as something that affects muscles, fat tissue, and the liver, the brain also relies on insulin to function properly.
When brain cells become resistant to insulin, they may struggle to use glucose efficiently. Over time, this can contribute to inflammation, oxidative stress, and changes in brain function that may increase the risk of memory loss and cognitive decline.
The Connection Between Metabolic Health and Brain Health
Research has consistently shown that people with Type 2 diabetes and insulin resistance have a higher risk of developing Alzheimer's disease and other forms of dementia.
Several factors may help explain this connection:
Chronic high blood sugar can damage blood vessels that supply the brain
Insulin resistance can increase inflammation throughout the body.
Poor glucose control may contribute to oxidative stress, which can damage cells.
Metabolic dysfunction may affect the brain's ability to clear harmful proteins associated with Alzheimer's disease.
This doesn't mean that everyone with diabetes will develop dementia. However, it highlights the importance of maintaining good metabolic health throughout life.
Risk Factors for Type 3 Diabetes
Many of the same factors that increase the risk of Type 2 diabetes may also increase the risk of cognitive decline, including:
Insulin resistance
Obesity
Prediabetes or Type 2 diabetes
High blood pressure
High cholesterol
Physical inactivity
Poor sleep
Chronic inflammation
These conditions often occur together and can place stress on both the body and the brain.
Can Type 3 Diabetes Be Prevented?
There is currently no guaranteed way to prevent Alzheimer's disease, but improving metabolic health may help reduce risk and support long-term brain function.
Healthy lifestyle habits that may benefit both metabolic and cognitive health include:
Eating a balanced, nutrient-dense diet
Staying physically active
Maintaining a healthy weight
Managing blood sugar levels
Prioritizing quality sleep
Controlling blood pressure and cholesterol
Avoiding smoking
Managing stress
Even small improvements in these areas can have positive effects on overall health.
Why This Matters
The concept of Type 3 diabetes highlights an important message that the health of the brain and the health of the body are closely connected.
When we think about metabolic health, we often focus on blood sugar, weight, or diabetes prevention. However, the same habits that support healthy metabolism may also help protect cognitive function as we age.
As research continues, one thing remains clear: taking steps to improve metabolic health today can benefit multiple aspects of health for years to come.
Key Takeaway
Type 3 diabetes is a term used to describe the potential link between insulin resistance in the brain and Alzheimer's disease.
While more research is needed, maintaining healthy blood sugar levels and supporting overall metabolic health may play an important role in protecting both body and brain function. Helping our patients improve their metabolic health is a core part of our mission at Covenant Metabolic Specialists.
Our team is dedicated to providing personalized, evidence-based care that empowers patients to make meaningful, lasting improvements in their health. Every patient deserves the tools, support, and guidance needed to achieve their goals, and we are honored to be part of that journey.
References
de la Monte SM, Wands JR. Alzheimer's disease is Type 3 diabetes—evidence reviewed. Journal of Diabetes Science and Technology. 2008;2(6):1101-1113.
Kciuk M, et al. Alzheimer's Disease as Type 3 Diabetes: Understanding the Role of Insulin Resistance and Impaired Glucose Metabolism. International Journal of Molecular Sciences. 2024.
de Oliveira Andrade LJ, et al. Brain insulin resistance and Alzheimer's disease: a systematic review. Arquivos de Neuro-Psiquiatria. 2024.
Arnold SE, et al. Brain insulin resistance in type 2 diabetes and Alzheimer's disease: concepts and conundrums. Nature Reviews Neurology. 2018;14(3):168-181.
Chapple B, et al. Type 3 Diabetes: Linking Insulin Resistance to Cognitive Impairment. Biomolecules. 2025.
Affuso F, et al. Insulin Resistance, a Risk Factor for Alzheimer's Disease. Biomedicines. 2024;12(8):1888.
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