Impairment in insulin and insulin growth factor seems to play a role in the development of Alzheimer's disease.
When you see the term “type 3 diabetes,” one may think it’s simply another type or form of diabetes. This is at least what I thought when Dr. Ronald Peterman, a clinical pharmacy specialist, initially introduced me to this topic. I would have never thought that type 3 diabetes was an alias for Alzheimer’s disease (AD).
Impaired insulin and insulin growth factor (IGF) production seems to play a role in the development of AD. Just like there are insulin genes being expressed in our pancreas, an insulin gene is also expressed in the adult human brain.1
Appropriately controlling blood glucose may not only prevent diabetic complications such as neuropathy, but could also potentially reduce enhancing patient progression to AD.
A study showed that type 2 diabetes and impaired fasting glucose occur significantly more frequently in patients with AD than in patients that did not have AD.1 People that have insulin resistance, in particular those with type 2 diabetes have an increased risk of suffering from Alzheimer's disease estimated to be between 50% and 65% higher.2 A patient with diabetes may be at an increased risk of developing AD, but no direct causation has been found. It was found that diffuse and neuritic plaques were similarly abundant in the brains of patients with type 2 diabetes and no type 2 diabetes.1 Neurofibrillary tangles, common characteristic in patients with AD, were not increased in type 2 diabetes patients thus inhibiting the assumption of type 2 diabetes causing AD. 1
Various in vitro and in vivo experiments performed by multiple researchers has led to the conclusion that neuronal cell survival and homeostatic function is dependent on the integrity of insulin and IGF signaling mechanism in our brain.1 Insulin and IGF are crucial for neuronal plasticity, synaptic capabilities, and acetylcholine production.1 Deficiency in insulin production has a negative impact on the brain over time.
There is no evidence stating that having type 2 diabetes or even type 1 diabetes causes AD. Many researchers believe that having type 2 diabetes may enhance the progression to AD. Managing diabetes is important enough in the sense that our goal is to prevent patients from developing complications such as neuropathy, nephropathy, or retinopathy. Considering type 2 diabetes progression to type 3 diabetes makes it even more important to appropriately manage a patient’s blood glucose. Diabetes prevention or effective management may help prevent AD and other dementias.3
To help reduce the risk of progressing to type 3 diabetes, it is important to continuously stress exercise and proper diet. Managing diabetes with medications can only get health care professionals so far. Without the patients’ effort in making healthier lifestyle choices, it can be impossible to appropriately manage blood glucose, even with high doses of insulin. It truly is a joint effort between the healthcare professional and patient.
Some questions that arise from this notion of type 3 diabetes and AD is that would proper healthy lifestyle choices early in life prevent AD from occurring? Also, how come everyone does not develop AD? Genetics may play a factor in development, but could eating healthy from the get go reduce chances of developing AD? Further studies are going to have to be performed in order to conclude a causative relationship between diabetes and development of AD.
For further coverage from the fields of Alzheimer’s disease and dementia, check out PharmacyTimes' sister site, NeurologyLive. The site's condition-specific page serves as a resource for the latest clinical news, articles, videos, and the most recently released data.
1. De la Monte SM, Wands JR. Alzheimer’s Disease Is Type 3 Diabetes—Evidence Reviewed. J Diabetes Sci Tech. (Online). 2008;2(6):1101-1113.
2. Type 3 diabetes. Diabetes.co.uk. Available at http://www.diabetes.co.uk/type3-diabetes.html Accessed July 18, 2017
3. Diabetes and Alzheimer's linked. Mayoclinic. Available at http://www.mayoclinic.org/diseases-conditions/alzheimers-disease/in-depth/diabetes-and-alzheimers/art-20046987?pg=2 Published March 26, 2016. Accessed July 18, 2017