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.

What is Type 3 Diabetes?

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.

Symptoms of Type 3 Diabetes

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.

Causes of Type 3 Diabetes

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:

1. Insulin Resistance

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.

2. Type 2 Diabetes

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.

3. Environmental and Lifestyle Factors

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.

Treatments for Type 3 Diabetes

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.

Can Type 3 Diabetes Be Prevented?

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.

Climate change and rapid urbanization are changing mosquito habitats, and shifting dengue serotypes are reshaping the disease landscape in India. As a result, the country is now witnessing a transformation in how dengue spreads, who it affects, and how severe infections can become.

Once considered a seasonal monsoon illness, dengue is now increasingly becoming a year-round public health challenge, extending into hill states, semi-urban regions, and previously low-risk geographies.

In an exclusive interview with HealthandMe, Dr. Shikha Taneja Malik, Senior Scientific Affairs Manager, Drugs for Neglected Diseases initiative (DNDi), South Asia, discussed why India’s dengue numbers are likely being massively undercounted, how surveillance and diagnostic gaps are masking the real scale of the crisis, and why young adults are facing more severe infections due to changing serotypes.

Dr. Shikha also explained the urgent global push for affordable therapeutics and the challenges India still faces in developing an indigenous dengue vaccine despite its strong manufacturing capacity.

Here are the excerpts from the interview:

Q. Dengue was always called a monsoon disease. Is that label now dangerously misleading?

Dr. Shikha: Yes, I would argue that labels are not just outdated but risky, too. What we are seeing across India and across the region is a fundamental shift in the transmission pattern.

Dengue used to follow a fairly predictable seasonal curve — cases would spike between July and November, track the monsoon, and then recede. That curve is flattening. We are now seeing cases in February, March, and May — months that were previously considered safe. Delhi, Mumbai, Bengaluru — cities that used to have clear off-seasons for dengue — are reporting year-round transmission.

Warmer temperatures, altered rainfall patterns, unplanned urbanization, and poor sanitation have lengthened transmission seasons, making dengue a year-round systemic crisis. Models now predict year-round transmission in coastal regions, though monsoon months will retain the highest peak.

Also read: National Dengue Day 2026: India Reports 6,927 Cases And 10 Deaths In 2026

Q. Are serotype shifts driving changing dengue patterns, especially in young adults?

Dr. Shikha: Yes, India is witnessing active serotype shifts, and they directly explain rising severity, especially in young adults. Initial infection with one of the four dengue serotypes results in lifelong immunity to that specific serotype. Whereas, a secondary infection with a different serotype can trigger Antibody-Dependent Enhancement (ADE).

Young adults who were exposed to one serotype in childhood are now encountering a new dominant serotype, making them especially vulnerable to severe secondary infections.

Q. Is India undercounting dengue cases? Why do so many cases go unreported?

Dr. Shikha: The 2.89 lakh figure in 2023 is what our surveillance system captures, but it is almost certainly a fraction of the true burden. The Lancet has estimated that India accounts for around 33 per cent of the global dengue burden, and globally, we are looking at approximately 400 million infections every year. That puts India's real annual dengue burden potentially in the tens of millions — not hundreds of thousands.

Few studies have shown that the estimates of actual cases are approximately 282 times higher.

There are several reasons why cases go unreported, and they compound each other.

• A large proportion of infections are either asymptomatic or present as a generic fever — patients never seek formal care.
• Our surveillance system is passive and fragmented. Reporting is largely dependent on public health facilities.
• Confirmatory testing through NS1 antigen tests or PCR requires infrastructure that is not yet uniformly available at the primary health center level, particularly in rural and semi-urban areas.

Q. Are previously dengue-free regions in India now reporting cases due to climate change?

Dr. Shikha: Yes, the geographic spread is both significant and well-documented. Climate change is playing a major role in this shift. Rising temperatures, changing rainfall patterns, increasing humidity, and rapid unplanned urbanization are creating more favorable conditions for Aedes aegypti mosquitoes to survive and transmit the virus for longer periods each year.

Since the mid-1990s, dengue has rapidly spread to regions where it was historically non-existent, including Odisha, Arunachal Pradesh, and Mizoram. In the early 2000s, dengue was endemic only in a few southern and northern states; it has since spread to many states, including union territories.

Read More: Ebola Outbreak: Rare Bundibugyo Strain Confirmed In DR Congo And Uganda

The shift is particularly visible in hilly and cooler geographies such as Himachal Pradesh and Jammu & Kashmir. Climate modelling projects further expansion of Aedes albopictus into upper Himalayan regions, including Leh-Ladakh and Arunachal Pradesh, by 2050.

Q. What are the biggest challenges in indigenous dengue vaccine production in India?

Dr. Shikha: India has strong vaccine manufacturing capacity, but dengue remains scientifically complex. Existing vaccines have limitations and do not cover all vulnerable groups.

India’s first Phase 3 trial for an indigenous dengue vaccine, DengiAll, is underway across 18 states. The Butantan vaccine candidate, originally developed by NIH, has been licensed to Indian companies, including Panacea, SIIPL, and Indian Immunologicals, with the ICMR-Panacea candidate being the most advanced.

The recent DCGI approval of Qdenga is encouraging, but sustained financing and coordination between ICMR, DBT, and industry will be critical for developing a truly indigenous vaccine.

Dengue has become one of the fastest-emerging health crises in the urban parts of India. Every year during the monsoon season, the number of dengue cases rises dramatically in many Indian cities, posing a huge burden on the healthcare sector.

Though climate and mosquitoes are usually cited as reasons for the surge in dengue cases, the problem actually lies in how urban life and the infrastructure of the cities have changed over the decades.

Why Urban Areas Are More Vulnerable

The dengue virus is spread through the Aedes aegypti mosquito that lives well in fresh still water, which is abundant in urban areas.

Mosquitoes breed in construction sites, open water tanks, old plastic buckets, flower pots, coolers, water stored on roofs, and blocked drainage systems. Due to the growing size of cities and high population density, mosquito-borne diseases have become more common.

There are many factors that contribute to the rise in the number of dengue patients, one of which is unplanned city expansion. The fast pace of development in the cities results in stagnant water in the construction areas going unnoticed for weeks.

Moreover, improper drainage and a lack of sanitation facilities help mosquitoes breed. Even posh societies and offices can suffer if proper checks are not conducted.

Urban lifestyle trends also act as indirect factors contributing to the issue. Longer working hours, higher levels of indoor activities, and reliance on mechanical ventilation lead to less focus on environmental hygiene issues.

Families tend to take mosquito prevention steps only after an outbreak starts. The overuse of plastics and poor waste management practices in urban areas have exacerbated waterlogging problems.

The situation has been exacerbated by climate change and global warming. Mosquitoes can breed at a faster pace and survive for a longer period of time in the warm climate and unpredictable rain patterns. Another factor that plays an important role is urban heat islands, which refer to places that are hotter because of man-made concrete buildings.

What Needs to Change?

In order to curb the incidence of dengue, there must be an all-around transformation, both on the part of the governing authorities and the people. Firstly, urban planning should take into consideration good drainage facilities, frequent fogging, garbage disposal services, and proper regulation of building sites. Secondly, there must be frequent checks in residential areas, schools, offices, markets, and open public areas.

Secondly, the awareness campaign needs to be practical and more community-oriented. The citizens should realize that the prevention of dengue starts from their homes. Actions like washing the coolers once a week, covering the water tank, not allowing the water to stagnate, and using mosquito repellents will go a long way in minimizing the spread of dengue.

Early Detection and Healthcare Preparedness

Healthcare preparedness is also equally important. The early detection and proper treatment of dengue could help avoid any serious complications. One should never overlook symptoms like fever, body pain, headache, rashes on the skin, nausea, and weakness during the rainy season.

Combatting dengue fever is no longer just a matter of health care but rather a question of urban planning and lifestyle issues. As the cities continue to expand, everyone should unite and come up with healthier and more environmentally friendly cities. Otherwise, we may see more recurring problems of dengue outbreaks in urban settings every year.

Amid growing discussions around hantavirus transmission through body fluids, experts today stressed that cases involving transmission through breast milk or semen remain extremely rare and should not trigger unnecessary panic.

The discussions began after a 2023 study published in the journal Viruses found that the Andes strain of the rat-borne virus can persist in human semen for up to six years.

More concerning was the possibility that the virus could potentially be transmitted sexually even after a person has recovered, according to the peer-reviewed study.

The research, conducted by Swiss scientists at Spiez Laboratory, suggested that hantavirus may survive in the male reproductive tract like viruses such as Ebola.

“Taken together, our results show that the Andes virus has the potential for sexual transmission,” the study said. However, to date, no confirmed case of such transmission has been documented.

Why Viral RNA Can Persist In Semen

Speaking to HealthandMe, Dr. Rajeev Jayadevan, convenor of the IMA research cell, explained that the detection of Andes virus RNA — the hantavirus strain linked to the recent MV Hondius cruise ship outbreak — in semen long after recovery is not entirely unexpected.

“The finding of RNA belonging to the Andes virus in human semen long after recovery is no surprise. In fact, this is a well-described scenario in at least 27 different viruses, including Zika and Ebola,” he said.

He explained that viruses reaching the testis enter what is known as an “immune-privileged” site protected by the blood-testis barrier (BTB).

“The testis is naturally shielded from the body’s immune system to protect newly formed sperm cells from being recognised and destroyed as ‘foreign’,” Dr. Rajeev said.

According to the expert, many viruses take advantage of this natural immune protection, allowing them to remain in the area longer than expected.

However, he clarified that although researchers detected viral RNA in semen, the virus itself could not be cultured, meaning there is no proof that the infectious virus remained present.

Also read: Ebola Outbreak: Rare Bundibugyo Strain Confirmed In DR Congo And Uganda

Can Hantavirus Spread Via Breast Milk?

Another study published in Emerging Infectious Diseases, a monthly open-access peer-reviewed medical journal published by the US Centers for Disease Control and Prevention, highlighted the risk of mother-to-child transmission of the Andes strain of hantavirus through breast milk.

Andes virus (ANDV) is the only hantavirus known to spread between humans through close contact.

“We detected the genome and proteins of ANDV in breast milk cells from an infected mother in Chile who transmitted the virus to her child, suggesting gastrointestinal infection through breast milk as a route of ANDV person-to-person transmission,” the study said.

Epidemiologist Dr. Amitav Banerjee, professor at DY Patil Vidyapeeth, Pune, told HealthandMe that while isolated cases of hantavirus transmission from mother to child through breast milk have been reported, they are highly uncommon.

“These cases of hantavirus transmission through breast milk from mother to child are very rare. As a general rule, there is no need to worry excessively,” he said.

According to him, mothers experiencing fever during the acute stage of illness may temporarily avoid breastfeeding because viral load tends to be highest during active infection and just before symptoms appear. However, he stressed that breastfeeding should not be stopped routinely out of fear.

Dr. Amitav explained that the situation is somewhat comparable to HIV transmission through breast milk, which also occurs in less than 1 percent of cases. Despite that, mothers in many developing countries are still advised to continue breastfeeding because the health risks of depriving infants of breast milk are often greater than the risk of viral transmission.

He noted that hantavirus differs significantly from HIV because it is generally an acute and transient infection, unlike HIV, which persists lifelong in body fluids.

“Hantavirus infection is acute and transient, whereas HIV is lifelong,” he said, adding that hantavirus usually clears from the body after recovery, including from semen and other body fluids.

Sexual Transmission After Recovery Still Unclear

Dr. Rajeev noted that the Andes virus spreads primarily through close contact and shared personal space while a patient is symptomatic.

“Whether it can be sexually transmitted long after recovery remains unknown,” he said.

Overinterpreting RT-PCR Results

Dr. Amitav also cautioned against overinterpreting isolated reports of viral detection in semen or breast milk.

According to him, RT-PCR tests are extremely sensitive and may detect dead viral particles even after the infection has resolved. Therefore, a positive RT-PCR result does not necessarily mean that a person remains infectious.

“In fact, RT-PCR is highly sensitive and often used more for research and surveillance purposes. Detecting viral material does not always indicate active infection or transmission risk,” he said.

He added that hantavirus does not appear to persist as an infectious virus for a long period after recovery and that there is currently no strong evidence supporting long-term transmission once a patient has recovered.