Is Alzheimer's type 3 diabetes? No, not officially. “Type 3 diabetes” is a research label some scientists use to describe problems with insulin signaling in the brains of people with Alzheimer's disease. It is not a medical diagnosis, it has not been adopted by the American Diabetes Association, and it is different from type 3c diabetes, which involves the pancreas.
Key takeaways
- A 2024 research review states that “type 3 diabetes” is not an officially recognized medical or diagnostic category and is not used in clinical coding.
- The term came from research by Suzanne de la Monte's group, who found insulin-related problems in the brains of people with Alzheimer's disease who did not have diabetes.
- The ADA's 2026 classification lists type 1, type 2, specific types due to other causes, and gestational diabetes. There is no type 3.
- Alzheimer's disease and diabetes are linked: ADA 2026 reports higher Alzheimer's rates in people with diabetes, and the link appears to run both ways.
- In November 2025, Novo Nordisk reported that oral semaglutide did not slow early Alzheimer's disease in two phase 3 trials.
What Does “Type 3 Diabetes” Mean?
“Type 3 diabetes” is a term some researchers use for the idea that Alzheimer's disease involves a kind of insulin resistance and insulin shortage inside the brain. A 2024 review in the International Journal of Molecular Sciences by Mateusz Kciuk and colleagues states plainly that the term is not an officially recognized medical or diagnostic category.
The review adds that the term has not been adopted by major health organizations such as the World Health Organization or the American Diabetes Association, and it is not used in clinical coding. It calls type 3 diabetes a theoretical concept that some researchers use to highlight overlap between Alzheimer's disease and type 2 diabetes.
So if you read that Alzheimer's “is” type 3 diabetes, treat it as shorthand for a research idea, not a diagnosis you or a family member could be given.
Where Did the Term Come From?
The term came from laboratory research by Suzanne de la Monte, MD, MPH, and colleagues at Brown University. In a 2008 review in the Journal of Diabetes Science and Technology, de la Monte and Jack Wands, MD, explained how their studies of brain tissue from people with Alzheimer's disease found problems with insulin and related growth factors in the brain.
Those brain changes looked similar to the effects of type 1 or type 2 diabetes, even though none of the patients studied had either disease. That led the researchers to propose that Alzheimer's disease may be a brain-specific form of diabetes, which they called type 3 diabetes.
The same review also noted limits. The authors wrote that type 2 diabetes causes brain insulin resistance, oxidative stress, and cognitive impairment, but that its combined effects fall far short of mimicking Alzheimer's disease. In other words, the original idea was not that type 2 diabetes turns into Alzheimer's disease. It was that the Alzheimer's brain shows its own insulin-related problems, which were found even in people without diabetes.
How Is Type 3 Different From Recognized Types of Diabetes?
The American Diabetes Association's Standards of Care in Diabetes—2026, Section 2 lists four broad categories of diabetes. ADA adds that these categories are being reconsidered as researchers learn more about genetic, metabolic, and other features. Type 3 diabetes is not among them.
| Term | Official status | What it refers to |
|---|---|---|
| Type 1 diabetes | ADA category | Autoimmune destruction of the cells that make insulin, usually leading to a lack of insulin |
| Type 2 diabetes | ADA category | A gradual loss of insulin production, often alongside insulin resistance |
| Specific types due to other causes | ADA category | Includes single-gene diabetes, diseases of the exocrine pancreas, and drug- or chemical-induced diabetes |
| Gestational diabetes | ADA category | Diabetes found in the second or third trimester of pregnancy that was not clearly present before |
| Type 3c diabetes | Informal name within specific types | Diabetes from disease, injury, or removal of the exocrine pancreas |
| Type 3 diabetes | Not an official category | A research label for insulin-signaling problems in the Alzheimer's brain |
The names sound alike, but they describe different things. Type 3c is an informal name for a recognized form of diabetes caused by pancreatic disease. Type 3 diabetes is not a recognized form of diabetes at all. Our guide to how many types of diabetes there are covers the recognized types, and type 1 vs type 2 diabetes compares the two most common.
How Are Alzheimer's Disease and Type 2 Diabetes Connected?
The connection between the two conditions is real, even though the label is not official. ADA 2026 Section 13 reports that people with diabetes have higher rates of Alzheimer's disease, vascular dementia, and all-cause dementia than people without diabetes. People with Alzheimer's disease or other dementias are also more likely to develop diabetes. ADA says this possible two-way link points to metabolic processes that contribute to brain cell damage.
The National Institute on Aging (NIA) says scientists are looking at the role of metabolic diseases, such as diabetes and obesity, in Alzheimer's disease. NIA also notes that age is the biggest known risk factor, and that fewer than 10% of cases occur before age 65. The causes probably include a mix of age-related brain changes along with genetic, health, and lifestyle factors.
Insulin resistance, where the body's cells do not respond well to insulin, is a feature of type 2 diabetes. Researchers continue to study whether insulin resistance inside the brain plays a role in Alzheimer's disease. For the body-wide version, see what insulin resistance is and insulin resistance vs diabetes.
For the broader research on diabetes and memory, including vascular dementia and a newly recognized pattern called diabetes-related dementia, see our guide to whether diabetes causes dementia.
What Are the Limits of the Type 3 Idea?
The type 3 idea has helped researchers ask useful questions, but it has clear limits:
- It is not a diagnosis. No one receives a type 3 diabetes diagnosis in routine care, and the term is not used in clinical coding.
- Alzheimer's disease can occur without diabetes. The brain studies that led to the term came from people who did not have type 1 or type 2 diabetes.
- Type 2 diabetes is not the same as Alzheimer's disease. The researchers who coined the term wrote that the brain effects of type 2 diabetes fall far short of mimicking Alzheimer's disease.
- Alzheimer's has many contributing factors. NIA points to age-related brain changes, genes, health conditions, and lifestyle factors, not one single cause.
- A major medicine trial was negative. The 2025 semaglutide trials described below did not slow early Alzheimer's disease.
What Did the 2025 Semaglutide Trials Find?
Researchers have also tested whether diabetes medicines might help people with Alzheimer's disease. On November 24, 2025, Novo Nordisk announced top-line results from its evoke and evoke+ phase 3 trials. The trials enrolled 3,808 adults aged 55 to 85 with mild cognitive impairment or mild dementia due to Alzheimer's disease.
Oral semaglutide, a GLP-1 receptor agonist used for type 2 diabetes, did not slow disease progression compared with placebo on a standard dementia rating scale called the CDR-SB. The medicine improved some Alzheimer's-related biomarkers, but that did not translate into a delay in disease progression. The company discontinued the planned one-year extension of both trials.
These results apply to people who already had early Alzheimer's disease. They do not tell you whether a medicine you take for diabetes affects your own brain health. ADA 2026 notes that some glucose-lowering drug classes have shown small benefits on slowing cognitive decline in studies, so research continues. Do not start, stop, or switch a medicine because of this news; ask your care team if you have questions.
What Does This Mean for You?
If you have type 2 diabetes, the type 3 label does not mean you have or will develop Alzheimer's disease. What the research does support is more practical: diabetes is one of several dementia risk factors that you can discuss with your care team.
- Blood pressure and cholesterol. ADA 2026 reports that blood pressure management and cholesterol lowering with statins have been associated with a lower risk of dementia.
- Low blood sugar. ADA reports that severe lows have been linked to a higher risk of dementia. Ask whether your medicines can cause lows and what your plan is.
- Memory screening. ADA recommends screening adults with diabetes aged 65 and older for mild cognitive impairment or dementia at the first visit, then every year and as appropriate.
- Hearing, sleep, mood, and activity. NIA lists hearing loss, depression, poor sleep, physical inactivity, and social isolation among factors linked to brain health.
A daily type 2 diabetes checklist can help keep routine care tasks in one place. If you need a regular clinician for these conversations, our guide to finding a diabetes doctor near you explains where to start. For the full picture, see how diabetes affects the brain, and for day-to-day fogginess, see whether diabetes can cause brain fog.
When Should You Get Help?
Emergency: Call 911 for sudden confusion, trouble speaking, face drooping, one-sided weakness, vision loss, or a seizure, or if someone with diabetes cannot be woken or cannot swallow. Give nothing by mouth to someone who cannot swallow safely.
Same day: Contact your care team the same day after any low that needed someone else's help, or if lows keep happening.
Prompt appointment: Book a visit for memory or thinking changes that last, get worse, or affect daily tasks, or that family members notice. A clinician can look for treatable causes and decide whether further testing is needed. Do not self-diagnose from a label.
Frequently Asked Questions
Is Alzheimer's type 3 diabetes?
Not officially. Type 3 diabetes is a research label some scientists use for insulin signaling problems in the Alzheimer's brain. A 2024 review notes that it is not a recognized medical or diagnostic category and has not been adopted by the World Health Organization or the American Diabetes Association.
What is type 3 diabetes?
Type 3 diabetes is a term used by researchers including de la Monte and Wands, who in a 2008 review described Alzheimer's disease as a possible brain-specific form of diabetes involving insulin problems in the brain. It is a theoretical concept, not a diagnosis, and it is not used in clinical coding.
Is type 3 diabetes the same as type 3c diabetes?
No. Type 3c is a name often used for diabetes caused by disease, injury, or removal of the pancreas, which ADA groups under specific types of diabetes due to other causes. Type 3 diabetes is an unofficial research label for Alzheimer's disease. The names sound alike but describe different things.
Does type 2 diabetes cause Alzheimer's disease?
Research links diabetes to a higher risk of Alzheimer's disease and other dementias, and the link appears to run both ways. Scientists have not shown that type 2 diabetes directly causes Alzheimer's. NIA notes that age is the biggest known risk factor. A higher risk does not mean Alzheimer's will happen.
Can diabetes medicines treat Alzheimer's disease?
Large trials have tested this. In November 2025, Novo Nordisk reported that its phase 3 evoke trials of oral semaglutide did not slow disease progression in people with early Alzheimer's disease. ADA 2026 notes small benefits on cognitive decline for some drug classes in studies, so research continues. Medicine decisions belong to your care team.
What should I do if I am worried about Alzheimer's?
Talk with your clinician about the specific changes you have noticed. ADA 2026 recommends memory screening for adults with diabetes aged 65 and older at the first visit and every year. NIA notes that memory problems can have other causes, such as medicine side effects, sleep problems, or infections, and some are treatable.
References
- Kciuk M, et al. “Alzheimer's Disease as Type 3 Diabetes: Understanding the Link and Implications.” International Journal of Molecular Sciences. 2024;25(22):11955. Accessed October 2026.
- de la Monte SM, Wands JR. “Alzheimer's Disease Is Type 3 Diabetes–Evidence Reviewed.” Journal of Diabetes Science and Technology. 2008;2(6):1101–1113. Accessed October 2026.
- American Diabetes Association Professional Practice Committee for Diabetes. “2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2026.” Diabetes Care. 2026;49(Suppl. 1):S27–S49. Accessed October 2026.
- American Diabetes Association Professional Practice Committee for Diabetes. “13. Older Adults: Standards of Care in Diabetes—2026.” Diabetes Care. 2026;49(Suppl. 1):S277–S296. Accessed October 2026.
- National Institute on Aging. “What Causes Alzheimer's Disease?” Accessed October 2026.
- National Institute on Aging. “Alzheimer's Disease Fact Sheet.” Accessed October 2026.
- Novo Nordisk A/S. “Novo Nordisk A/S: Evoke phase 3 trials did not demonstrate a statistically significant reduction in Alzheimer's disease progression.” GlobeNewswire, November 24, 2025. Accessed October 2026.
- Meng X, et al. “From Xiaoke to diabetes mellitus: a review of the research progress in traditional Chinese medicine for diabetes mellitus treatment.” Chinese Medicine. 2023;18:75. Historical context only for the companion feature. Accessed October 2026.
Next Steps
If a headline about type 3 diabetes worried you, bring your questions to your next visit. Ask about your blood pressure and cholesterol goals, your plan for lows, and, if you are 65 or older, whether a memory screening is due.
For adults with type 2 diabetes or prediabetes who want lifestyle education alongside clinical care, the Done With Diabetes™ program, a type 2 diabetes protocol, organizes learning about meals, movement, sleep, and stress. It does not diagnose or treat diabetes, dementia, Alzheimer's disease, or other brain conditions, interpret symptoms or test results, change medicines, or replace your care team.