What Is Type 3 Diabetes? Doctors Explain How Insulin Resistance May Increase Alzheimer’s Risk

You’re likely already familiar with type 1 and type 2 diabetes, conditions in which the body either can’t make insulin or can’t use insulin properly. Now, the term “type 3 diabetes” is making headlines and sparking debate in the medical community. Some experts propose it as a term to describe the potential link between diabetes and Alzheimer’s disease. We spoke with healthcare professionals to learn more about this complex topic, including what causes type 3 diabetes, its symptoms, treatment options and prevention strategies.

What is type 3 diabetes?

While not an officially recognized form of diabetes, “type 3 diabetes is a term some researchers use to describe how insulin resistance in the brain might contribute to Alzheimer’s disease,” explains James Lyons, MD, Medical Consultant for Synergy Houses. The brain, he continues, relies on insulin to properly process glucose (blood sugar). “If the brain becomes resistant to insulin, it can struggle to use glucose effectively, which may lead to cognitive decline over time.”

Dr. Lyons says type 3 diabetes risk factors include “[having] type 2 diabetes, your genetics, chronic inflammation and even lifestyle choices.”

The link between diabetes and Alzheimer’s disease

Type 3 diabetes remains a controversial term in the medical field. This is primarily due to limited research and a lack of a clinical definition. But Dr. Lyons notes that “while not everyone agrees on calling Alzheimer’s ‘type 3 diabetes,’ the link between metabolic health and brain health is well-documented.”

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One theory revolves around insulin. “Diabetes and Alzheimer’s are closely connected because insulin is essential for both blood sugar regulation and brain function,” explains Gowri Rocco, MD, MS, Founder of Optimum Wellness and Longevity. Studies have shown that brain tissue in Alzheimer’s patients exhibits insulin resistance, similar to type 2 diabetes. “When insulin resistance develops in the brain, glucose metabolism is impaired, leading to amyloid plaque buildup and neurofibrillary tangles, both associated with Alzheimer’s,” says Dr. Rocco.

As discussed above, Dr. Rocco adds that “people with type 2 Diabetes face a much higher risk of developing Alzheimer’s, highlighting the impact of metabolic dysfunction on neurodegeneration.” High blood sugar levels, oxidative stress and chronic inflammation associated with diabetes can damage blood vessels and nerves in the brain. 

How to treat type 3 diabetes

“The symptoms associated with type 3 diabetes mirror those of early Alzheimer’s, like memory loss, confusion, trouble concentrating and mood changes,” says Dr. Lyons. If you or a loved one are experiencing these symptoms, consult a healthcare professional for a proper evaluation.

“Since there’s no official diagnosis, treatments focus on managing risk factors,” continues Dr. Lyons.” Lifestyle changes and managing diabetes remain “the best strategies.” These include “keeping blood sugar under control, eating a healthy diet (the Mediterranean or DASH diet are great examples), exercising regularly and addressing other conditions like high blood pressure or obesity.”

“A low-glycemic, high-fat and high-protein diet—especially a ketogenic approach—helps stabilize blood sugar and reduce inflammation,” adds Dr. Rocco. Similarly, “strength training is particularly beneficial, as it increases insulin sensitivity and supports protective hormone production.”

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Dr. Rocco also highlights stress management and sleep optimization (such as establishing a consistent sleep routine). Chronic stress, she explains, “exacerbates inflammation and accelerates cognitive decline,” while quality sleep supports “memory consolidation and brain detoxification.” 

The bottom line on type 3 diabetes

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You can take proactive steps to protect your mind and body as you age. “If you’re a woman over 50, your metabolic health directly impacts your brain health,” underscores Dr. Lyons. “Managing conditions like type 2 diabetes, high blood pressure or cholesterol isn’t just about protecting your heart—it’s also about protecting your mind.”

While you can fully reverse Alzheimer’s, Dr. Rocco adds that a “proactive approach, including nutrition, exercise and mindfulness, can significantly reduce risk and support long-term cognitive function.”

If you’re concerned about type 3 diabetes or Alzheimer’s disease, consult with a healthcare professional. They can evaluate your symptoms, review your medical or family history and recommend appropriate tests and treatment options. “Early action is key, and simple steps can go a long way in protecting your cognitive health,” says Dr. Lyons.