Why Alzheimer’s Disease Can Be Called “Type 3 Diabetes” and How to Prevent It

preventing alzheimer's disease

In today’s first world countries, most people live in abundance. This should be and is a great blessing to everyone who experiences the comfort it brings. This truly is one of the best times to be alive. We can drive to the grocery store and spend a fraction of our income to obtain all the food we need. Humans before us wouldn’t know what to do with themselves.

grocery store abundant unhealthy foodHowever, this also gets us into trouble. While modern society has developed in many positive ways, we are still the same humans as our ancestors who were built solely to survive off whatever resources were available to them.

We all have the instinct to splurge on food as if we did not know when the next time it would be seen. However, nutrients are always available, and if this habit continuously repeats itself with unhealthy foods, we have a real problem on our hands.

We see this problem manifest itself daily as a detriment to our health. Humanity brings more disease upon itself through lifestyle choice than ever before. The list of well-known diseases that can be self-inflicted include obesity, heart disease, diabetes, and many more, but how lifestyle plays into the health of our brains isn’t spoken of as often. What about diseases such as Alzheimer’s Disease (AD), which is projected to afflict as many as 13.5 million people by 2050?

The Story of Alzheimer’s as Type 3 Diabetes

I was reading a review article by Song, Whitcomb, and Kim about how intertwined AD and diabetes are and what they spoke of was stunning. They discussed how new information about AD points towards it really being “Type 3 diabetes”. A diabetes of the brain.

For me personally, AD always seemed sort of mystical. It just happened to some people as they aged and there was no specific cause or anything we could do about it. I have known a few people with the condition and hoped that it never happened to me in old age.

With this new research, I don’t think I will experience it, and if you read this information carefully, you could possibly reduce your risk as well. Before we get to that, however, a bit of a story needs to be told about why exactly AD is being called Type 3 Diabetes.

Shared Risk Factors Between Alzheimer’s Disease and Diabetes

People with Type 2 Diabetes have a much higher chance of getting AD than the average person. There are even some common characteristics that are true to almost every case of Type 2 Diabetes (T2D) and to AD. Let’s dive into some of the details.

Insulin Resistance

Due to a constant influx of sugar from poor dietary choices, the pancreas is forced to produce more and more insulin to get glucose out of the blood and into cells where it can either be burned immediately or converted to fat for energy storage.

Insulin resistance from too much sugar alzheimersHowever, our pancreas and cells weren’t meant to handle copious amounts of sugar. In a healthy person, there should only be about a teaspoon of sugar in our blood. What happens when we eat a bag of candy that contains 10, 15 or 20 teaspoons worth of sugar? The pancreas spits out insulin to clear it out, but if this happens consistently, our cells become insulin resistant.

Science hasn’t nailed down all of the reasons for why this happens, but our cells stop being able to use insulin efficiently and more is required to shuttle away the same amount of sugar. That is why people with T2D are in a dire condition; their bodies have broken and cannot process sugar properly.

In addition to this, the pancreas begins to malfunction. In a time when we need MORE insulin due to insulin resistance, the workload on the pancreas is already too high which leads to a slow shutdown. The result is high blood sugar which is why diabetics need medication.

At this point, you may be wondering how this relates to the brain. Well, it has been shown that the progression of AD depends on the brain’s ability to use glucose, its main source of energy. Unfortunately, the effects of insulin resistance don’t just stay below the neck. Our brains become insulin resistant as well which makes them unable to make as much energy.

Even without looking at AD, this inability of the brain to get energy causes a general cognitive decline in many people with T2D. Although we mainly talk about insulin’s sole purpose being blood sugar regulation, it becomes very different in the brain. Be prepared, this is where it gets very, very interesting.

Older adults alzheimers preventionInsulin and the Brain

In the brain, insulin has a protective effect and is even responsible for memory. On the protective side of things, insulin resistance has been shown to harm neuron cells inside the hippocampus (which is responsible for much of our long-term memory). This makes sense when we think about some of the symptoms of AD such as memory loss.

“Insulin is known to be neuroprotective and has powerful effects on memory”

In a few different studies, the hippocampus has been shown to regulate memories through the use of insulin. The hippocampus is lined with insulin receptors (things on the edge of cells that catch molecules of insulin) which become damaged through insulin resistance as well. On average, patients with AD have about 80% fewer insulin receptors than a healthy person.

To be a bit more straightforward, studies have shown that deficiencies in insulin receptors directly lead to memory dysfunction. Insulin resistance in the brain has been shown to stunt chemicals that function to help new neurons grow and proteins that increase memory and learning ability are unable to be activated. Even more, molecules that increase the number of misfolded proteins are made which could lead to the characteristic harmful plaques that are seen in the brains of AD patients.

“insulin resistance and impaired insulin signaling are significantly related to tau hyperphosphorylation and Aβ deposition (plaque buildup) in AD, and ultimately contribute to cognitive decline”

Since there is a lot of information packed in a tight space above, here is a quick summary:

Insulin resistance harms the brain because…

  • Insulin receptors (especially in the hippocampus) are damaged.
    • Insulin receptors are the main way the brain can use insulin.
  • Cells in the brain don’t get enough energy from glucose.
  • Proteins that promote neuron growth and survival are stunted.
  • Molecules that are involved in learning and memory cannot get activated.
  • Proteins misfold and form harmful plaques.

High Blood Sugar and the Brain

Damage to the brain in people with AD from symptoms shared with diabetes doesn’t stop with insulin resistance. Since the pancreas doesn’t make enough insulin, the high blood sugar dilemma also causes problems in the brain. Luckily for us, this part is a bit more straightforward.

unhealthy brain alzheimersToo much glucose flowing through the brain has been shown to harm the cells that make up the blood-brain barrier (BBB). You’ve most likely heard of the BBB, but in short, it is a fortress of cells that decides very selectively what is able to go in and out of the brain. When this defense mechanism is harmed, holes open up that allow unwanted molecules and proteins into the brain.

Some of these unwanted proteins are misfolded and form the plaques that we have heard about a few times already. Although we don’t completely understand how and why these plaques form, scientists are fairly certain that insulin resistance and hyperglycemia (high blood sugar) play a big role.

“hyperglycemia-induced BBB disruption might play an important role in the onset and progression of AD”

Another side effect of having hyperglycemia is that harmful radicals are formed. These radicals can go on to do many negative things such as causing us to age and harm our DNA, but most importantly for the brain, they increase inflammation. This increase in inflammation has also been associated with the build-up of plaques and consequently lowers cognitive ability and diminishes memory even further.

“Type 3 diabetes (Alzheimer’s Disease) is related to the prevalence of [Type 2 Diabetes] and results from insulin resistance and hyperglycemia”

We Aren’t Helpless in This Fight For Our Brains

The description about AD given above may make the situation for many of us seem a bit dismal. After all, the CDC reports that over 100 million people are diabetic or prediabetic in America alone. However, I think that knowing what causes AD is more empowering than fearful. Instead of hoping you don’t just become another statistic, there are ways that we can live that can greatly reduce our risk.

melatonin for brain healthMelatonin and the Fight Against AD

When reading the common risk factors for diabetes, most of them (insulin sensitivity, hyperglycemia, etc.) make sense, but one stood out to me that didn’t: sleep trouble. Why would problems sleeping be a risk factor for diabetes?

It turns out that melatonin does much more than regulate sleep. When your circadian rhythm is out of tune from a lack of melatonin, having trouble sleeping is just a warning sign for much larger problems. No, you won’t just have less energy throughout the day from not sleeping as well, but melatonin also plays a crucial role in some of the risk factors for AD and T2D. There is some amazing new research detailing melatonin’s importance that was described by the same review paper.

How Does Melatonin Help Us?

Interestingly, 45% of patients with AD have trouble sleeping which points towards them having a problem with their melatonin. It turns out melatonin is quite the molecular superhero when it comes to the brain, acting as a protector that can break up plaque accumulation while simultaneously helping synapses to function properly.

Melatonin has also been shown in a multitude of studies to lower insulin resistance and regulate blood glucose levels, both of which are enormous problems that lead to AD and T2D. Furthermore, melatonin is even starting to be prescribed to patients with AD as a viable treatment option.

As if this wasn’t enough to validate melatonin, it also can help to reduce some of the inflammation caused by hyperglycemia in the brain. In mice, melatonin supplementation has been shown to reduce some of the memory loss caused by AD as well. This makes sense as it specifically improves synapse function in the hippocampus where much of our memory is held.

“Melatonin may be a key to improving memory function by suppressing the cell damage induced by Aβ toxicity and tau hyperphosphorylation”

How to Use Melatonin To Our Advantage

The paper only detailed how melatonin helps, so the following is my personal recommendation. We now know that maintaining healthy melatonin levels and a regular circadian rhythm is crucial to fending off some of the risk factors for T2D and AD. So, let’s do this!

We can make changes to our lifestyle to keep melatonin and circadian rhythm in check. Yes, genetic factors do play a role, but we really can’t do anything about that (yet) but you CAN make lifestyle changes to combat this. Here’s what you should do based off other research I have studied:

  • Go to sleep at the same time every night no matter what day of the week it is.
  • Put away electronics at least 45 minutes before bed.
  • Exercise in the morning.
  • Eat a healthy diet that allows your body to function properly
    • It has been shown that allowing hyperglycemia and insulin resistance to occur in your body can harm circadian rhythm and melatonin production.
  • Take supplements that boost melatonin and help circadian rhythm

For more depth on how to get the best sleep possible, read more here.

healthy lifestyle to prevent alzheimersLive the Lifestyle Your Body Deserves

While melatonin is an important factor to consider when thinking about how to give yourself the best chance of avoiding T2D and AD, the elephant in the room is that our lifestyle choices remain the largest risk factor for T2D and, from new research, possibly AD.

In the average person, hyperglycemia and insulin resistance are simply caused by eating an unhealthy diet and not exercising enough. Going back to the introduction of this article, our current environment of abundance and comfort provides us with the ability to live the best life possible, but it can be abused.

The most important thing that we can do is eat less sugar and processed foods while making sure to exercise regularly. It’s very straightforward, but hard to put into practice. For me, sacrificing some comfort and pleasure is worth lowering my risk of T2D and AD along with many other chronic diseases.


In the end, it comes down to what you want for your future and where your priorities lie. Alzheimer’s disease is being called “Type 3 Diabetes” because we are learning that it shares many risk factors with diabetes. If you take anything away from this, it should be a sense of empowerment because you can make decisions that will lower your chance of being afflicted with these diseases and make choices that will improve your quality of life. So, enjoy the benefits of modern society but get good sleep and most importantly, live a healthy life if you want to protect your brain.

What is your experience with these diseases?

What have you been successful with?