What Is Type 3 Diabetes?

You are probably familiar with Type 1 diabetes. It is an autoimmune condition that attacks the pancreas, making it unable to produce enough insulin. Most people also know about Type 2 diabetes, where the cells in the body become resistant to insulin, resulting in high blood sugar levels.

Research¹ is increasingly pointing to the possibility of a third type of diabetes and how it is related to a common and serious health problem: Alzheimer's Disease (AD). This new kind of diabetes is sometimes called diabetes of the brain, but it is more accurately referred to as Type 3 diabetes.

What is Type 3 diabetes?

It's important to note that AD is caused by more than one factor, and these causes can vary. A small percentage of cases are caused primarily by genetics, but for most people, it is caused by a combination of genetic and environmental factors.

One of those environmental factors appears to be the conditions that lead to insulin resistance. Insulin resistance is when the cells in the body become less able to use insulin, preventing it from efficiently moving glucose from the blood into the cells.

It's been shown that insulin resistance causes damage in the body, and it can lead to problems such as damage to the back of the eye, liver disease, and polycystic ovarian syndrome. 

It's beginning to look like the same condition may also cause cellular and molecular changes that lead to AD. For some people, insulin resistance creates a cascade of problems that specifically impact the brain. Scientists are calling this Type 3 diabetes. 

What are the causes and risk factors?

The main risk factors for AD are age and a family history of dementia. That is, the older you get, the higher your risk of developing AD becomes, and if the disease runs in your family, that also raises your risk. Other factors include having depression, vascular problems, experiencing severe head trauma, low education levels, and being female.

Though most people with AD have a genetic predisposition toward the disease, genes alone aren't enough to cause it. Some people are genetically susceptible to developing AD, but insulin resistance is what starts the process.

In the case of Type 3 diabetes, elevated levels of blood sugar, usually caused by insulin resistance in the body, lead to oxidative stress. This oxidative stress becomes overwhelming and can no longer be balanced out by antioxidants in the body, leading to free radicals that damage cells. This damage has been well documented in people with Type 2 diabetes or even subclinical levels of insulin resistance. 

For some people, these negative effects seem to be concentrated in the brain. The brain is particularly susceptible to this damage for a few reasons. It's rich in polyunsaturated fatty acids, which are fragile to the effects of oxidation.

On top of that, the brain has lower amounts of antioxidants than the rest of the body. 

This oxidative stress attacks the cells, but it also seems to contribute to the formation of excess tau proteins and the neurofibrillary tangles that identify disease markers of AD.  Deposits of amyloid-beta protein have been found in the pancreas of people with Type 2 diabetes. A similar protein has been found to deposit in the brain tissue of people who have AD.

The signs and symptoms of Type 3 diabetes

According to a systematic review² of the scientific literature on AD, it is a difficult condition to diagnose until the later stages of the disease. However, there are frequently occurring symptoms to look out for.

As many as 99.1% of patients experienced depression and cognitive impairment as their first symptoms. Memory loss can often be seen 12 years before a diagnosis of AD. Other common signs include myoclonus or quick, involuntary muscle twitching or jerks, muscle rigidity, and abnormal gait. 

People often have difficulty completing tasks, and they frequently misplace items. They may show a sudden change in personality and exhibit poor judgment.

These signs, along with a diagnosis of insulin resistance or diabetes, suggest that a patient is experiencing dementia, which may be caused by Type 3 diabetes. 

How is Type 3 diabetes diagnosed?

The science on type 3 diabetes is developing, and there is currently no test to determine if that is what is causing a patient's dementia. In general, it is often a challenge to get a diagnosis until AD is fairly far progressed. 

Once a patient has been diagnosed with AD, additional lab tests to determine if the patient has insulin resistance or Type 2 diabetes may suggest that they have type 3 diabetes. It isn't yet considered an official diagnosis, but treating insulin resistance is the first line of defense against type 3 diabetes, regardless of the diagnosis.

Are there treatments available?

Currently, there is no treatment for AD, although according to the National Institute on Aging, some medications may help manage symptoms. These include drugs to help slow the progression of dementia and antidepressants and anti-anxiety medications to help manage the mood swings and depression that often come with the disease. 

A new medication, called aducanumab, seems to reduce amyloid deposits in the brain. However, it hasn't yet been proven to improve symptoms or affect the disease's progression. 

There is research that suggests a possible therapy for type 3 diabetes. A study³ that insulin-sensitizing agents, such as the diabetes drug metformin, may reduce the risk of AD among patients with diabetes.

Another study suggests that insulin-sensitizing agents may even have a therapeutic effect, at least in the early stages of the disease. These drugs may prevent neurodegeneration. More research is needed, but the possibility is encouraging. 

Can you prevent type 3 diabetes?

Given the lack of treatments for type 3 diabetes, people at high risk for the disease need to do all they can to prevent the conditions that can lead to its development. Since the main driver of type 3 diabetes is insulin resistance, that is the most important factor to focus on. 

The brain uses 20%⁴ of the glucose in the body. Unlike other body parts, brain cells can only use glucose for fuel. This makes the fight against insulin resistance even more important to reduce the oxidative stress of high blood sugar and ensure that the brain gets the fuel it needs to function at its best.

Exercise is an important way to battle insulin resistance. Working out makes all the cells in the body more sensitive to insulin, allowing them to use it more effectively, keeping blood sugar levels in check. This increase in insulin sensitivity lasts around 72 hours, so it is best to get some exercise at least every two to three days. 

You should try to get a minimum of 150 minutes of moderate-intensity workouts every week. The best exercise schedule includes both cardio and strength training. Balance exercises, such as yoga or Tai Chi, can also help with the instability and increased falls that often come with AD.

Combining regular exercise with a healthy diet can also help. Focus on foods that are low in saturated fat, high in protein, and high in fiber. Healthy choices that contribute to blood sugar control will help stave off the impacts on the brain caused by type 3 diabetes. 

On top of these measures, you can add other activities that have been shown to reduce your risk of AD. These include mental stimulation, such as puzzles, social activity, good sleep habits, and stress management. 

The lowdown

New scientific research suggests that insulin resistance may be an important factor in the development of AD. This condition is referred to as type 3 diabetes, and it seems to explain the damage that occurs in the brains of people with AD. 

Although there are currently no treatments specifically targeting type 3 diabetes, there are ways you can fight insulin resistance, potentially reducing your risk of AD.