What is Type 3 Diabetes? An In-Depth Look

Diabetes is a chronic health condition characterized by high blood sugar levels. For many years, diabetes was classified into two main types - type 1 and type 2. However, research over the past decade has identified another form of diabetes, now known as type 3 diabetes.

Type 3 diabetes is a term used to describe Alzheimer's disease that involves insulin resistance in the brain. Some researchers theorize that Alzheimer's disease is a new type of diabetes that specifically affects the brain. Let's take an in-depth look at what type 3 diabetes is, its connection to Alzheimer's, and how it differs from other forms of diabetes.

What is Type 3 Diabetes?

Type 3 diabetes is not yet an officially recognized medical condition. The term was first coined in 2005 by researchers to describe the strong link between diabetes and Alzheimer's disease.

Just as diabetes is caused by insulin resistance in the body, type 3 diabetes is thought to be caused by insulin resistance in the brain. This prevents brain cells from getting the energy they need from glucose, leading to deteriorating brain function.

Some key things to know about type 3 diabetes:

  • It is an unofficial term used to classify Alzheimer's disease as a form of diabetes affecting the brain.
  • Insulin resistance in the brain is believed to be a contributing factor to Alzheimer's disease.
  • The brain cannot effectively use insulin or glucose, depriving brain cells of energy.
  • It is not yet recognized as an official medical diagnosis or type of diabetes.

The Connection Between Type 3 Diabetes and Alzheimer's

Research over the past few decades has uncovered several links between diabetes and Alzheimer's:

Insulin Resistance

Insulin resistance is common in those with type 2 diabetes. Studies show insulin resistance also occurs in the brains of those with Alzheimer's disease, preventing brain cells from getting glucose for energy.

Brain Shrinkage

Brain scans show that those with diabetes have a smaller brain size, similar to reductions seen in Alzheimer's patients. Autopsies also show that Alzheimer's patients have significantly reduced insulin levels in the brain.

Plaque Formation

Diabetes is associated with atherosclerosis, the plaque buildup in blood vessels. Autopsies show similar plaque formation occurs in the brains of Alzheimer's patients.


Chronic inflammation occurs in both diabetes and Alzheimer's disease. Researchers believe inflammation is a key driver of insulin resistance and plaque buildup in the brain.

Genetic Factors

Many genes linked to type 2 diabetes are also associated with an increased risk of Alzheimer's. This suggests shared genetic risk factors.

Key Differences Between Type 3 Diabetes and Other Forms

There are a few key differences between type 3 diabetes and other established forms of diabetes:

  • Type 1 diabetes is an autoimmune disease where the pancreas cannot produce insulin. Type 3 diabetes is caused by insulin resistance in the brain.
  • Type 2 diabetes involves insulin resistance in the body's tissues (liver, fat, muscle). Type 3 diabetes is specific to insulin resistance in the brain.
  • Gestational diabetes occurs during pregnancy but goes away after birth. Type 3 diabetes is not tied to pregnancy.
  • Prediabetes means blood sugar levels are higher than normal but not high enough for a diabetes diagnosis. There is no "pre" stage for type 3 diabetes.
  • Other forms like steroid-induced diabetes or monogenic diabetes involve very specific causes. Type 3 diabetes has a broader focus on all Alzheimer's cases influenced by insulin resistance.

The key similarity between type 3 and other forms is the central role insulin resistance plays in disease progression. But type 3 diabetes is specific to the brain.

Signs and Symptoms of Type 3 Diabetes

There are no unique symptoms specifically associated with type 3 diabetes. Since it is another term for Alzheimer's disease, the symptoms are the same:

  • Memory loss that disrupts daily life
  • Challenges in planning or solving problems
  • Difficulty completing familiar tasks
  • Confusion with time or place
  • Trouble understanding visual images and spatial relationships
  • New problems with words in speaking or writing
  • Misplacing things and losing the ability to retrace steps
  • Decreased or poor judgment
  • Withdrawal from work or social activities
  • Changes in mood and personality

These symptoms get progressively worse over time in Alzheimer's disease. The rate of progression can vary quite a bit from person to person.

Who Is at Risk for Type 3 Diabetes?

Research shows several factors that increase the risk of developing type 3 diabetes:

Age - The risk goes up dramatically with age. Most people with Alzheimer's disease are diagnosed at age 65 or older.

Family History - Those with a parent, sibling or child with Alzheimer's are more likely to develop the disease. Genetics play a role.

Down Syndrome - People with Down syndrome are at a significantly higher risk of Alzheimer's disease.

Lifestyle Factors - Lack of exercise, obesity, smoking, and a diet high in saturated fats are linked to increased risk.

Head Trauma - Previous severe head injuries may increase the risk.

Cardiovascular Disease - Heart disease, stroke, high cholesterol and high blood pressure can increase the risk.

Insulin Resistance - Those with prediabetes or type 2 diabetes are at greater risk.

The biggest risk factors are non-modifiable - mainly age and genetics. But living an overall healthy lifestyle may help reduce your risk.

Can Type 3 Diabetes Be Prevented or Delayed?

There is no surefire way to prevent type 3 diabetes. However, leading a brain-healthy lifestyle may help delay or reduce your risk.

Exercise regularly - Exercise may directly benefit brain cells and is linked to reduced risk of dementia. Try for at least 150 minutes per week.

Eat a balanced diet - Focus on fruits, vegetables, whole grains, fish, poultry and healthy fats like olive oil. Avoid saturated and trans fats.

Get proper sleep - Lack of sleep is linked to amyloid plaque buildup in the brain, a hallmark of Alzheimer’s disease. Aim for 7-8 hours per night.

Manage health conditions - Properly manage high blood pressure, cholesterol, and especially diabetes to reduce dementia risk.

Stay socially and mentally active - Engage in social activities and mentally stimulating hobbies to strengthen brain connectivity.

Avoid smoking and limit alcohol intake - Both are associated with higher dementia risk.

Use caution with medications - Discuss any necessary medications with your doctor as some may raise dementia risk.

While these steps can't guarantee prevention, they may help delay cognitive decline and reduce your overall risk. Check with your doctor for personalized recommendations.

Diagnosing Type 3 Diabetes

There are no specific diagnostic criteria or blood tests for type 3 diabetes. Since it refers to Alzheimer's disease with insulin resistance as an underlying cause, diagnosis relies on a combination of:

  • Medical history - The doctor will ask about any symptoms, family history of dementia, and other medical conditions like diabetes.
  • Physical exam - Assessing signs like memory, problem-solving skills and neurological function.
  • Blood tests - To help rule out other causes and check indicators like blood glucose and HbA1c levels.
  • Brain imaging - CT scans or MRIs to look for indicators like shrinking in certain brain regions.
  • Cognitive assessments - Paper-and-pen or computerized tests to evaluate memory, thinking skills, and cognitive decline.
  • Psychiatric evaluation - To check for conditions like depression or vitamin deficiencies that could mimic dementia.

There are no blood tests that can definitively diagnose Alzheimer's disease or type 3 diabetes at this point in time. Doctors diagnose it based on a combination of ruling out other causes and evaluating cognitive decline.

Available Treatments for Type 3 Diabetes

Currently, there is no cure for Alzheimer's disease or type 3 diabetes. Treatment focuses on managing symptoms to slow the rate of decline.

Some medication options include:

  • Cholinesterase inhibitors like donepezil or rivastigmine to increase acetylcholine levels in the brain. This neurotransmitter is important for memory and thinking.
  • NMDA receptor antagonists like memantine to regulate glutamate levels and protect nerve cells.
  • Insulin or other diabetes medications may be used off-label in some cases to try improving insulin function in the brain. But results are mixed.

Non-drug therapies can also help slow symptoms, such as:

  • Cognitive training exercises to practice memory, problem-solving, and other thinking skills.
  • Occupational therapy to find new ways to manage daily activities.
  • Physical therapy to maintain mobility and reduce fall risk.
  • Speech therapy for communication difficulties.
  • Counseling or support groups for emotional and behavioral issues.

Research is ongoing to find more effective treatments that address the root causes of Alzheimer's disease and type 3 diabetes. Insulin sensitizers, plaque-clearing drugs, neuroprotective agents, and anti-inflammatories show promise.

Current Outlook for Type 3 Diabetes

While recognizing Alzheimer's disease as a type of diabetes is still controversial, it has stimulated valuable research. The links between insulin resistance, inflammation, cardiovascular disease, and dementia continue to be investigated.

This research will hopefully fuel breakthroughs in diagnosing and treating Alzheimer's disease. Blood tests to detect biomarkers of brain insulin resistance could lead to much earlier diagnosis and intervention. New drugs targeting downstream effects of insulin resistance and inflammation may also provide benefits.

In the meantime, following a brain-healthy lifestyle gives you the best chance to lower your risk or delay onset of cognitive decline. See your doctor regularly for checkups, memory screening, and managing conditions like prediabetes or high blood pressure. Staying physically, socially, and mentally active also appears protective against dementia.

Hopefully a greater understanding of the connections between Alzheimer's and diabetes will unlock new insights and therapeutic strategies. While type 3 diabetes is not yet a clinically defined condition, recognizing the parallels with other forms of diabetes may open doors to eventually better diagnosing and treating this debilitating disease.

Frequently Asked Questions About Type 3 Diabetes

What causes type 3 diabetes?

Type 3 diabetes is not yet an official medical diagnosis, but is thought to be caused by insulin resistance in the brain leading to the memory loss and cognitive decline seen in Alzheimer's disease. The exact mechanisms linking insulin resistance to Alzheimer's are still being researched.

Is type 3 diabetes genetic?

There do appear to be genetic factors that increase risk of type 3 diabetes, since family history raises Alzheimer's risk. But lifestyle factors like diet, exercise, cardiovascular health also play a major role, especially in late-onset Alzheimer's disease.

Can you get type 3 diabetes without having Alzheimer's disease?

No, type 3 diabetes is simply a term used by some researchers to classify Alzheimer's disease as a form of diabetes specific to the brain. The memory loss and dementia must be present for a diagnosis of Alzheimer's disease.

Is there a test for type 3 diabetes?

There is currently no blood test or brain scan that can definitively diagnose Alzheimer's disease or type 3 diabetes. Doctors rely on a combination of memory tests, cognitive assessments, ruling out other causes, and looking for brain changes like shrinking in certain regions.

Should I get tested for type 3 diabetes?

Unless you are experiencing cognitive decline, there is no screening test available to diagnose type 3 diabetes or predict risk of Alzheimer's disease with accuracy. Leading a brain-healthy lifestyle is the best way to lower your risk.

How is type 3 diabetes treated?

There is no cure for Alzheimer's disease or type 3 diabetes. Treatment focuses on managing symptoms with medications like cholinesterase inhibitors and NMDA receptor antagonists. Non-drug therapies like occupational therapy, physical therapy, and cognitive training may also help slow progression.

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