What Is Type 3 Diabetes? Insulin Resistance In The Brain That Could Trigger Alzheimer’s
Most people are aware of type 1 and type 2 diabetes, but did you know there is a type 3 diabetes as well! It is a more obscure term. Although it is not an accepted medical diagnosis, type 3 diabetes has been discussed in the literature as a possible relationship between insulin resistance in the brain and Alzheimer's disease. This link has been described to help explain how metabolic disorders impact brain health, causing cognitive decline and dementia.
Type 3 diabetes is more of a misnomer because it should not be confused with type 3c diabetes, which relates to pancreatic dysfunction. The term "type 3 diabetes," on the other hand, has been loosely used by some scientists to analogously propose that Alzheimer's disease is strongly implicated with insulin resistance in the brain.
This concept was conceptualized by Dr. Suzanne de la Monte and Dr. Jack Wands of Brown University in the year 2008. This hypothesis postulated that Alzheimer's disease may be called type 3 diabetes for it bears many similarities with glucose metabolism disorder type 2 diabetes. Their concept arises from the basic principle that insulin is fundamental to blood sugar regulation, but it is also the case with the brain. When brain cells become insulin-resistant, they lose access to glucose, impairing their function.
Research published in the Journal of Diabetes Science and Technology supports this hypothesis by indicating that insulin resistance can be a significant contributor to the occurrence of dementia, also referred to as Alzheimer's. The symptoms of memory loss and diminished reasoning are associated with impaired glucose metabolism in the body, especially in the cerebral tissue.
Although type 3 diabetes is not a "medical term," its symptoms correlate well with Alzheimer's diseases that are known to reduce the ability to think in an efficient manner and bring down brain health. These signs are:
- Loss of memory, especially short-term.
- Poor judgment and judgment ability
- Failure in recognizing people or places familiar once.
- Failure in the process of reading, writing or processing numbers
- Anxiety, agitation, or mood changes.
- Disorganized thoughts or confusion
- Lack of impulse control
As the disease advances, patients may be afflicted with severe complications including an inability to swallow or control their bodily functions. In the final stages, most patients die from fatal complications such as aspiration pneumonia.
This may not be well understood with regards to type 3 diabetes, or the exact link between insulin resistance and Alzheimer's disease. Some identified contributing factors include the following:
Insulin acts as an important regulatory mechanism of brain functions such as memory and cognition. The reduction in insulin signaling may impair metabolism of brain cells, thus bringing about neurodegeneration.
These diseases show a strong relationship and those individuals diagnosed with type 2 diabetes have double chances of getting Alzheimer's. In the two, the main causes can be chronic inflammation, oxidative stress, and a defect in glucose metabolism.
Insulin resistance associated with obesity, stress, and an unhealthy diet is considered a cause that may increase the chances of Alzheimer's disease.
Researches in Frontiers in Neuroscience and The Lancet Neurology have also highlighted that drugs used for antidiabetic medication may be crucial for the prevention or at least slowing down the course of Alzheimer's.
In 2022, in a study in Pharmaceuticals, researchers studied biomarker uptake in brain regions implicated in the faulty uptake and metabolism of blood sugar in Alzheimer’s patients.
Emerging Therapies
Research into such treatments as intranasal insulin has also been promising. Intranasal delivery of insulin directly to the brain has been reported to enhance glucose uptake by brain cells, improve memory, and boost cognitive performance. While such clinical trials have been shown to be successful, additional research is needed for safety and efficacy.
Medications
For patients being aggressive or agitated, antipsychotic drugs may be prescribed; however, therapies such as cognitive rehabilitation as well as cognitive stimulation therapy serve to preserve memory and executive function.
Lifestyle Interventions
Diet, exercise, and stress management are critical in preventing and managing insulin resistance. A review in the Journal of Alzheimer's Disease also highlighted the benefits of Kirtan Kriya meditation, which can regulate genes involved in insulin and glucose metabolism, improve sleep, and reduce inflammation.
Although type 3 diabetes is not officially recognized, its connection to Alzheimer’s disease underscores the importance of proactive measures for brain health. Some prevention strategies include:
1. Healthy Diet
Consuming a balanced diet rich in antioxidants, whole grains, and healthy fats may support brain health.
2. Regular Exercise
Physical activity improves insulin sensitivity, reduces inflammation, and enhances overall metabolic health.
3. Stress Reduction
Mindfulness practices, including meditation, have been shown to lower stress levels, which can reduce the risk of cognitive decline.
The term type 3 diabetes brings out the complex relationship between metabolic disorders and brain health. Even though it is not a recognized medical condition, the concept emphasizes the crucial role of insulin in brain function and its possible contribution to Alzheimer's disease. Continued research will hopefully provide hope for therapies such as intranasal insulin and lifestyle modifications.
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When Todd Engel, based in Maryland, first noticed a change in his vision, he did not think it would change the rest of his life. However, within months, the 62-year-old went from working a full-time job and driving to becoming legally blind in both eyes. Now, Engel is suing Novo Nordisk, the manufacturer of Ozempic - the drug he believes took away his vision.
Engel was prescribed Ozempic in 2023 to help manage his type 2 diabetes. After four months later, he was diagnosed with nonarthritic anterior ischemic optic neuropathy (NAION). It is a rare condition where blood flow to the optic nerve is blocked and causes sudden and irreversible vision loss.
"He made a comment to me about how it’s painful to know he’s never going to see his wife smile again," said Engel’s attorney Jonathan Orent, who spoke to NBC News. "But he knows her voice so well, he can tell when she is smiling."
As per the American Academy of Ophthalmology, NAION affects about 10 in every 100,000 people over the age of 50. For Engel, the diagnosis meant that he no longer would work his job as a motor equipment operator. He also lost his ability to drive and the way he connects with his family.
Filed in New Jersey’s Middlesex County Superior Court, the lawsuit accuses Novo Nordisk of negligence, alleging the pharmaceutical giant failed to properly warn users about the potential risk of NAION. Engel's legal team argues that the company was aware of the condition during early clinical trials but still chose not to include it in the warning label.
“Nothing was or is stopping Defendant from adding a warning regarding the risk of NAION,” the lawsuit states.
Had Engel known about a potential link between Ozempic and blindness, Orent said, he would have chosen a different medication. “There are a wide number of medications that can be used to treat diabetes — and treat it effectively,” Orent said to NBC News.
Ozempic, and its active ingredient semaglutide, is part of a class of drugs known as GLP-1 receptor agonists, initially designed to treat Type 2 diabetes but now widely used for weight loss. Recent studies have hinted at a possible link between semaglutide and NAION — though causation hasn’t been confirmed.
A 2024 study which analyzed six years of medical records from Boston patients found that people with diabetes who took semglutide were four times more likely to be diagnosed with NAION.
Even more striking, overweight or obese people without diabetes who took the drug were over seven times more likely to be diagnosed with NAION.
However, researchers noted this study wasn’t a randomized clinical trial and said more investigation is needed before drawing conclusions.
In February 2024, a separate paper published in JAMA Ophthalmology reported a more modest increase in the risk of NAION for people with diabetes on Ozempic. Like the earlier study, it also stressed the need for further research.
Novo Nordisk's spokeperson told the NBC News that current evaluations, including internal safety reviews and a study from the University of Southern Denmark found no causal relationship between NAION and Ozempic.
The company said that NAION is not listed as an adverse drug reaction. “This also relates to eye conditions, which are well-known comorbidities for people living with diabetes,” the spokesperson said.
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Ever thought those weekend binges, skipped workouts, or stress-fueled all-nighters in your 20s wouldn't matter later? Think again. The truth is, those early habits don’t just fade—they follow you. And by your 30s, they often come knocking in the form of low energy, poor sleep, creeping weight, or even anxiety. But here’s the good news: small, healthy choices now can completely rewrite that story. Ready to see how your everyday habits are shaping your future health? Let’s dive in.
It turns out the consequences of your twenties don't just haunt your social media feed—they may be silently impacting your long-term health well before you reach middle age. A groundbreaking study published in the Annals of Medicine has revealed that bad habits such as smoking, excessive alcohol consumption, and physical inactivity begin taking a measurable toll on mental and physical health by the age of 36.
This research, led by Finnish scientists and conducted over the course of more than 30 years, offers one of the most comprehensive glimpses yet into how unhealthy lifestyle choices in early adulthood accelerate aging and disease risks, and perhaps more crucially, when exactly those effects begin to show.
While much of previous research has focused on health deterioration starting in midlife, the new longitudinal study flips the script by starting earlier. Scientists from Finland followed over 300 individuals born in 1959 in the city of Jyväskylä from childhood into their early 60s. Health assessments were conducted at ages 27, 36, 42, 50, and 61, offering an unparalleled timeline of how unhealthy behaviors impact wellbeing over decades.
The researchers found that even by age 36—what many consider still "young adulthood"—participants who consistently smoked, drank heavily, and exercised infrequently already showed notable declines in both mental and physical health. This suggests that the damage doesn’t start in your 40s or 50s. It begins much earlier, and once set in motion, it compounds.
The three behaviors monitored—smoking, heavy alcohol use (defined as over 875 units/year for women and 1,250 for men), and exercising less than once a week—were assessed alongside health outcomes like depressive symptoms, psychological well-being, self-rated health, and a metabolic risk score that measured blood pressure, waist size, cholesterol, blood sugar, and other markers.
Dr. Tiia Kekäläinen, lead author of the study and a health scientist at Laurea University in Finland, emphasized the urgency of early intervention. “Our findings highlight the importance of tackling risky health behaviours as early as possible to prevent damage from building up over the years,” she explained.
One of the most compelling insights from the study is the recognition that the relationship between poor habits and poor health is likely two-way. A person under chronic stress may turn to drinking or smoking to cope, leading to more health issues, which in turn worsen stress and mental health—a vicious cycle.
This echoes similar findings from large-scale studies, such as the ongoing Nurses' Health Study and the Health Professionals Follow-up Study, conducted by the Harvard T.H. Chan School of Public Health. These studies emphasize the interconnected nature of diet, physical activity, and mental wellbeing across decades of life.
Interestingly, the study separated out which habits affected which aspects of health the most. Smoking was most closely tied to poor mental health outcomes, while lack of exercise impacted physical health most significantly. Heavy drinking, perhaps unsurprisingly, was associated with declines in both mental and physical wellbeing.
This finding is particularly relevant in a post-pandemic world where mental health concerns are on the rise among younger adults, and alcohol use among Americans has increased significantly, especially among women and young professionals.
Though the data primarily pertains to individuals born in the late 1950s and early 1960s, researchers caution that its findings are still broadly applicable. However, younger generations may face different lifestyle risks—such as increased screen time, vaping, and dietary imbalances—that weren't as prevalent in earlier cohorts. Therefore, the health impact timeline could shift, but the underlying message remains: the earlier you adopt healthier behaviors, the better.
High-profile figures like Adele, Rupert Grint, and A$AP Rocky—all around the age of 36—have publicly grappled with smoking and drinking. Adele, who quit smoking at 23, cited concerns about her vocal cords. Rupert Grint revealed he gave up smoking when his daughter was born in 2020. These personal transformations reflect a growing awareness among public figures of the need to shift lifestyle habits before long-term damage becomes irreversible.
Perhaps the most hopeful message from the study is that change is possible. Dr. Kekäläinen reiterates: “It is never too late to change to healthier habits. Adopting healthier habits in midlife also has benefits for older age.”
So, what are the takeaways for someone nearing or in their 30s?
Your 30s aren't just about career milestones or starting a family—they're a crucial checkpoint for your health journey. The choices you make today will echo through your 40s, 50s, and beyond.
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In mid-2023, the tech mogul and self-proclaimed biohacker, the anti-age crusader Bryan Johnson began a new chapter in his longevity journey. He is already known his extreme anti-aging regimen - Project Blueprint. He has turned his attention to something unconventional. However, it is a telling health metric: nighttime erections.
He has now started a daily dose of 2.5mg of tadalafil (Cialis). He has set out to track and enhance what he calls a crucial "vital sign". His goal is not performance, but optimization. He tells his followers on X, the results were "titanic".
By early 2024, Johnson had added focused shockwave therapy and Botox injections to the mix. Within three months, he says, his nighttime erections improved by 34%. It has clocked in at quite an impressive three hours, with biological equivalent of an 18-year-old.
While the idea of three-hour erections may sound like a punchline, Johnson is pretty serious about it. "Nighttime erections," he explains, "are a strong biomarker of cardiovascular, psychological, and sexual health." These spontaneous erections during sleep can reflect a man’s overall physical and vascular health.
What is interesting to see is that he also maintains that Cialis itself is unlikely to be the sole driver of his sexual function improvements. While the drug is FDA-approved to treat erectile dysfunction, Johnson says it mainly supports long-term health. His claims are that it helps with improved heart function, cognitive health, and reduced urinary symptoms in men.
In order to push his results further, Johnson also turned to shockwave therapy. This is a treatment that involves acoustic pulses delivered via a wand to the penis.
The shocks cause micro-injuries that stimulate blood flow and tissue repair - not unlike how muscles grow after a workout. However, it is not a spa day. Johnson rated that the pain is 7 on a scale of 10. When it is "at the tip", the pain goes up to 9 on a scale of 10.
Alongside the shockwaves, Johnson began Botox injections, which might sound bizarre but are backed by emerging science. Botox, typically used to reduce facial wrinkles, is thought to relax the smooth muscle in blood vessel walls, allowing more blood flow and potentially firmer erections.
ALSO READ: The Longevity Diet: Bryan Johnson Eats 3 Meals In 6 Hours—With Extra Virgin Olive Oil
After three months on this combined protocol, Johnson says his nighttime erections rose from 2 hours and 15 minutes to 3 hours. Despite the gains, he reportedly sleeps alone, keeps an 8:30 p.m. bedtime, and schedules sex, if at all.
His larger aim? To maintain all his organs — brain, liver, teeth, even his rectum — at peak teenage condition through strict diet, 111 daily supplements, and intensive routines.
While Johnson’s methods are extreme, he hopes they help reduce stigma. “Men, if you’re not performing how you’d like, there are many paths to improvement,” he said. “There’s no shame in this — in fact, it will make you more of a man to address it head-on.”
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