Type 3 Diabetes: The Alarming Link Between Alzheimer’s and Diet

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Picture of a Human Head With Cogs Representing a Brain.If you haven’t heard of it, type 3 diabetes is what many specialists are now calling Alzheimer’s disease.

The name covers the belief that Alzheimer’s results from insulin resistance of the brain.

Alzheimer’s is a cruel, degenerative condition that devastates millions of lives around the world.

And unfortunately, it’s only increasing in prevalence; as of 2016, 1 in 9 people over the age of 65 have Alzheimer’s.

Surprisingly, the number of individuals aged 65 and over with the condition is expected to triple by the year 2050 (1).

Could abnormal blood glucose and insulin regulation play a role?

This article takes a look at the metabolic theory of type 3 diabetes, and how we might be able to prevent (or potentially halt) the condition.

What is Type 3 Diabetes?

Type 3 diabetes—or Alzheimer’s disease—is a chronic condition in which brain neurons slowly degenerate and die (2, 3).

As a result, we see progressive memory loss and rapid declines in cognitive ability (4).

I’ve personally seen the terrible effects of Alzheimer’s. As a young boy, I remember seeing my great grandfather hospitalized with late-stage Alzheimer’s.

And then from the start of my late teenage years, I saw my granddad—a strong, well-built man—slowly succumb to the disease.

Sadly, the condition can hit anyone.

Someone being physically fit or having an intelligent mind is not relevant; the disease doesn’t discriminate, and it takes no prisoners.

A Cruel Condition

Experiencing a slow deterioration, patients eventually lose the ability to interact with their environment, communicate, and even remember their family.

Ultimately, Alzheimer’s disease is fatal, and patients usually die from a resulting complication such as pneumonia (5).

Worse still, it’s not only the patient that suffers.

Alzheimer’s caregivers often have to spend all their time and money to look after their family member, and it’s a very emotionally and physically demanding job.

Key Point: Alzheimer’s Disease is a devastating condition that is rapidly increasing in prevalence. It slowly and progressively robs people of their ability to think, move, communicate, and live everyday life.

An Old Man Looking Confused.Why is Alzheimer’s ‘Type 3 Diabetes’?

There are three types of diabetes:

  • Type 1 diabetes occurs when the pancreas cannot produce insulin.
  • When the body cannot produce enough insulin and becomes resistant to insulin, a type 2 diabetes diagnosis follows.
  • Type 3 diabetes is now being used to describe Alzheimer’s, due to the brain insulin resistance link. Generally speaking, diagnosis usually occurs in those over the age of 65, but the disease can develop over decades (6).

More and more researchers are saying that type 3 diabetes is one of the “diseases of civilization.”

This term refers to the fact that how we live our lives can significantly impact our health.

For instance, our diet, exercise plan, and sleep can either dramatically increase or reduce our risk of diseases such as:

  • Alzheimer’s
  • Cancer (some types)
  • Cardiovascular Disease
  • Diabetes
  • Rheumatoid Arthritis

These ‘diseases of civilization’ are part of the metabolic syndrome, and glucose and insulin dysregulation profoundly influence all of them (7).

The Harms of the Modern Western Diet

For the most part, these problems stemming from glucose and insulin issues relate to the food we eat.

And unfortunately, the modern Western—perhaps global—diet revolves around industrially processed food.

In fact, a study analyzing consumer purchases shows that 77% of all grocery purchases are either moderately (16%) or highly (61%) processed (8).

These foodstuffs contain significant amounts of sugar and refined carbohydrates, leading to large spikes in blood sugar and insulin levels.

Over time, this can lead to worsening insulin resistance and eventually, metabolic disease (9).

Key Point: What causes Alzheimer’s disease? While there may not be a single answer, the modern Western diet likely plays a huge role.

The Alarming Link Between Type 3 Diabetes and Diet

Cartoon Illustration Showing Various Unhealthy Foods.

As shown above, there is a strong connection between type 3 diabetes and the food we eat.

But what, precisely, does the science say?

Recent Research Findings

  • There is substantial evidence that impaired insulin signaling causes Alzheimer’s disease, which includes a deficiency in brain insulin. It is “justified to refer to Alzheimer’s as type 3 diabetes” (10).
  • An excessive amount of carbohydrate–especially fructose–and a deficiency of fat and dietary cholesterol may lead to Alzheimer’s disease (11).
  • Alzheimer’s disease has a high prevalence in Western society due to incorrect diet and poor lifestyle (12).
  • Strong evidence suggests that brain insulin resistance is a major contributor to Alzheimer’s. Particularly, abnormalities in biochemical, molecular, and signal transduction are almost the same as those seen in type 2 diabetes (13).
  • Alzheimer’s patients show “cerebral glucose hypometabolism”; this means that patients have an abnormally slow rate of utilizing glucose in their brain, possibly due to impaired insulin signaling (14).
  • Declines in the cerebral (brain) metabolic rate of glucose can begin in those with genetic risk for Alzheimer’s as young as their thirties. And impaired cell responses to insulin may be behind these declines (15).
  • Even in the early stages of Alzheimer’s, cerebral glucose utilization is reduced by up to 45% (16).
  • It is “prudent to recommend” those at risk of diabetes to avoid foods and beverages containing sugar and to eat whole foods full of naturally-occurring fats. Anyone with a family history should minimize any food that impacts blood sugar levels (17).
  • Patients with Alzheimer’s disease have a larger waist, lower levels of HDL, and higher circulating triglycerides. For those not aware, these are all markers for high blood glucose and insulin resistance (18).
  • A change in diet that focuses on decreasing dietary carbohydrate and increasing fat “may effectively prevent Alzheimer’s disease” (19).

The Effects of Brain Insulin Resistance

Illustration of a Human Brain.The studies above are just a small fraction of those that suggest blood sugar and insulin issues are causational in type 3 diabetes.

In simple English, these studies are saying that Alzheimer’s is a metabolic disease that progressively degrades the ability of our brain to respond to insulin.

As the brain becomes resistant to the effects of insulin, it can no longer efficiently utilize glucose.

When the brain cannot correctly use glucose, it builds up in the brain (hyperglycemia) and leads to oxidative stress and the formation of advanced glycation end products.

Both of these processes further damage the brain, promote accumulation of amyloid beta (plaque in the brain) and impair insulin signaling (20).

Importantly, our brain’s neurons will decline as the rate at which they can utilize energy (glucose) drops.

And eventually, they will die.

Key Point: There is a wealth of evidence suggesting that the pathology of Alzheimer’s disease strongly links to brain insulin resistance.

Further Evidence: Alzheimer’s Risk Factors

If we look at the risk factors for Alzheimer’s disease, then we can see a common pattern.

On the whole, the risk factors often relate to glucose dysregulation.

For example, here are some commonly accepted risk factors for Alzheimer’s disease:

Chronic Sleep DeprivationLack of Exercise
ObesityPoor Diet
Sleep ApneaSugar Intake

Each of these factors can negatively impact our risk of type 3 diabetes, and each one relates to how well we metabolize glucose.

A Sleep-Deprived Man Who Cannot Get To Sleep.Chronic Sleep Deprivation

  • Chronic sleep disturbances are a stressor that can trigger earlier onset of Alzheimer’s disease. The effects include memory impairment and damage to connections in the brain (21).
  • One week of sleep deprivation significantly reduces insulin sensitivity (22).

Lack of Exercise

  • In older adults with glucose intolerance, regular aerobic exercise leads to improvements in cognitive performance (23).
  • The “first line of defense” against Alzheimer’s is behavior that increases insulin sensitivity, such as physical exercise (24).


  • The epidemic of diseases relating to insulin resistance, such as obesity and type 2 diabetes, are “driving the significant increases in Alzheimer’s disease” (25).
  • Obese adolescents with insulin resistance have higher levels of circulating molecules that have links to increased risk of Alzheimer’s in the elderly (26).

A Man Eating Two Donuts - Chocolate and Strawberry.Poor Diet & Sugar Intake

  • The typical Western diet raises blood glucose levels, which has links to neurological deficits (27).
  • Insulin resistance may promote Alzheimer’s disease, and we can theoretically prevent the condition “by dietary measures to increase insulin sensitivity” (28).

Sleep Apnea

  • There is a theory that sleep apnea can increase insulin resistance. Additionally, a wealth of evidence suggests that sleep apnea has a causal relationship with dementia (29, 30).
Key Point: The major risk factors for type 3 diabetes all share a common link to glucose dysregulation and insulin resistance.

Can We Reverse Type 3 Diabetes With Diet?

Is type 3 diabetes curable?

Here is the official line:

At present, Alzheimer’s is a chronic, ultimately fatal condition with an inevitable, progressive decline.

Standard treatment options include Alzheimer’s medications that attempt to slow the progression of the disease and relieve symptoms.

The official line is that a little more time is the best we can hope for.

Replacing Glucose: Are Ketones the Key?

If our brain being unable to utilize glucose is a cause of Alzheimer’s disease, then what happens if we replace glucose with another fuel?

We often hear how glucose is essential for our brain, but this isn’t true at all. Our brain—and our body too—can operate on a source of energy called ketone bodies.

Simply known as ketones, the liver produces them when carbohydrate is in short supply. And the positive news is that our brain can function—thrive even—on this source of energy.

To achieve ketosis, we need a dietary system that focuses on cutting out sugar, starches, grains and foods with significant amounts of carbohydrate.

If we concentrate on healthy fats from coconut oil and olive oil and base our diet around dairy, fish, meat, and low sugar fruits and vegetables, then we will significantly limit our blood glucose levels, and the body will start to produce ketones.

A low carb diet—especially the ketogenic diet— is a perfect dietary system to achieve this aim.

So, Can We Reverse Alzheimer’s?

Unfortunately, at this time and as far as the research goes, it is thought that we cannot stop the disease from progressing.

Alzheimer’s develops over many years, and it is often asymptomatic in the early stages. Frequently, symptoms won’t even be noticeable to others until the middle stages of the disease (31).

Due to this, it might be too late to fight the disease by the time obvious symptoms appear.

However, if we catch it early enough, then who knows?

Halting or reversing the condition might be possible, but for now, there is no clear consensus or accepted science on this.

Ketones and Type 3 Diabetes: What Do Studies Show?

Looking at the research into ketones and Alzheimer’s, there have been some promising findings.

  • The glucose uptake of Alzheimer’s sufferers is vastly lower than age-matched healthy control subjects. However, this is not the case for brain ketone uptake—which is evenly matched in both Alzheimer’s patients and healthy controls (32).
  • Brain neuronal cells can metabolize ketones despite a deficiency of glucose. Also, ketogenic diets improve mitochondrial pathways to boost brain and neuronal metabolism (33).
  • A randomized controlled trial shows that Alzheimer’s patients taking a ketone supplement had a higher count of brain ketones. Additionally, they showed significantly improved brain cognition compared to patients not taking the ketone supplement (34).
Key Point: In short, dietary ketones allow energy-starved neuronal cells to gain energy from an alternative source. This energy helps improve brain performance.

Things We Can Do to Help Fight Type 3 Diabetes

Picture of An Elderly Couple Exercising Together With Dumbbells.

First of all, for any medical condition, it’s always best to consult with a medical professional.

However, it’s worth noting that Alzheimer’s medical interventions don’t treat the root cause of the disease and may “offer a lack of substantial benefit” (35).

With this in mind, many people feel that combining medical care with dietary and lifestyle strategies gets the best results.

Assuming brain insulin resistance is fueling the fire of type 3 diabetes, then taking steps to normalize blood sugar levels makes sense.

There are a number of ways through which we can do this, but diet, exercise, and sleep are the big three:


A way of eating that prioritizes nutrient-dense foods from fish, low sugar fruit, healthy fats, meat, and vegetables.

Diets that restrict starches and acellular carbohydrate sources like flours and sugars reliably reduce blood sugar levels (36).

And by following such a diet, drops in blood glucose levels should be accompanied by an increase in the production of ketones.


Physical exercise also helps regulate blood glucose.

  • High-intensity exercise helps reduce fasting blood glucose levels and improves insulin sensitivity (37).
  • A study following 5157 diabetic participants found that those doing the longest duration of exercise had the biggest decreases in blood sugar (38).

A healthy exercise program and getting some intense exercise several times per week may help in this regard.


Sleep is one of the most important considerations for our overall health, and it has a significant impact on glucose metabolism.

In fact, lack of sleep impairs glucose tolerance and decreases insulin sensitivity—even if it is over just two days (39).

A recent study compared subjects getting 10 hours sleep, versus those sleeping only 4 hours per night. In the state of sleep debt, there was a 40% decrease in insulin sensitivity (40).

Key Point: A dietary and lifestyle approach to improving insulin sensitivity and glucose metabolism should consider a suitable diet, exercise program, and sufficient sleep.

Prevention is Better Than Cure

One thing to remember about type 3 diabetes is that it doesn’t just suddenly happen when we hit our 60s.

In reality, the preconditions that lead to it start early in life and build progressively. As the saying goes, prevention is always better than cure.

Just like the way we live our life and the foods we eat have a tremendous impact on type 2 diabetes risk, it seems that this is also the case with Alzheimer’s disease.

By eating the right foods and adopting a healthy lifestyle now, we can tackle brain insulin sensitivity before it becomes problematic.

While we can never be sure, if we do this then we may be giving ourselves the best chance to avoid this dreadful disease.

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