Alzheimer's and Diabetes: What is Type 3 Diabetes?

Alzheimer's and Diabetes: What is Type 3 Diabetes?
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Type 1 diabetes, or insulin-dependent diabetes mellitus (IDDM), occurs most often in children and adolescents. It is a chronic condition in which the body’s immune system destroys beta cells in the pancreas that manufacture the hormone insulin. Without insulin, blood sugar cannot get into the cells of the body. This can lead to serious complications. People with type 1 diabetes require lifelong injections of insulin to control blood sugar levels.

Type 2 diabetes, or non-insulin-dependent diabetes mellitus (NIDDM), usually has an onset after forty years of age, and is often related to diet and lifestyle. The majority of people with this type of diabetes are obese, and this condition is becoming more common in younger individuals. With type 2 diabetes, either the pancreas does not produce enough insulin or the cells of the body become resistant to insulin. Although many people with type 2 diabetes take insulin or oral medications, many cases can be controlled by diet alone.

So what is type 3 diabetes? This form of diabetes, dubbed type 3 by the Brown Medical School (now called Warren Alpert Medical School) in Rhode Island, is not thought to affect blood sugar like type 1 and 2 diabetes does. Because of recent findings regarding brain insulin, it is now suggested that Alzheimer’s disease is not just a neurologic disorder, but rather a neuroendocrine disorder, thus giving this hybrid disease the term type 3 diabetes.

Recent Findings

It was recently discovered that the brain produces insulin which is necessary for the survival of brain cells. Research also found that brain insulin produced by people with Alzheimer’s disease tends to be below normal levels. In addition, it was discovered that low levels of acetylcholine, a neurotransmitter that is thought to be involved in learning and memory that is found in reduced levels in the brains of people with Alzheimer’s, are directly linked to the loss of insulin in the brain.

If insulin levels are below normal, cells will die. In the case of Alzheimer’s disease, the cells located in parts of the brain involved with memory, including the hypothalamus and hippocampus, die.

A characteristic symptom of Alzheimers is the formation of abnormal proteins, called ADDLs, that attach themselves to particular sites on synapses. Synapses are structures that permit neurons to pass an electrical or chemical signal to another cell, and are important for memory formation. Scientists from Northwestern University, Evanston, Illinois, USA, and the Universidade Federal do Rio de Janeiro in Brazil discovered that insulin may prevent or slow memory loss by blocking the action of ADDL proteins.

Can These New Findings Help Treat Alzheimer’s?

The above information shows promise in the treatment of Alzheimer’s disease, but more research is needed.

Several studies have been done using an intranasal insulin. In one study, people who were given 20 units of intranasal insulin two times a day retained more verbal information than those who were given a placebo. It was also noted that fasting blood sugar and insulin were not affected with intranasal insulin use.


According to J Diabetes Sci Technol. 2008 Nov;2(6):1101-13, “We conclude that the term “type 3 diabetes” accurately reflects the fact that AD represents a form of diabetes that selectively involves the brain and has molecular and biochemical features that overlap with both type 1 diabetes mellitus and T2DM.”

Sources Used

BBC News: Study suggests ‘type 3 diabetes’ -

Daily News Central: Alzheimer’s Disease May Be ‘Type3’ Diabetes -

U.S. Pharmacist: Type 3 Diabetes: Brain Diabetes? -

Medical News Today: Insulin May Protect Brain Against Alzheimer’s -

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