Type 3 diabetes is a new (and not quite accepted yet) term to describe the effects that diabetes can have on the brain. It describes the progression of diabetes to Alzheimer’s disease. The correlation between diabetes and Alzheimer’s is well documented, and this blog will aim to describe the proposed mechanism.

Just a quick reminder; diabetes is directly affected by insulin. There is either not enough insulin (type 1), or too much production due to insulin resistance (type 2). Type 2 diabetes is the one that is implicated in Alzheimer’s disease. 

Alzheimer’s is complicated, and the current understanding of the disease process postulates that progression is due to a build up of a protein called amyloid beta peptide. These form plaques that affect brain function. Your brain cells have receptors of insulin, so when it is released from the pancreas, it has a direct effect on the brain. When the brain becomes insulin resistant, more insulin has to be released to have the intended response. The plaques in patients with Alzheimer’s are formed in the space between nerves of the brain, not inside the nerves. An overabundance of insulin causes the nerves to release the amyloid beta protein into the space between the nerves (Gasparini et al., 2001). 

Alzheimer’s accounts for about 80% of all dementia. Vascular dementia is another form where the blood vessels aren’t functioning normally. There is a cause and effect relationship between hyperinsulinemia and hypertension. Insulin increases blood pressure by increasing sodium absorption in the kidneys, activating the fight or flight nervous system, and causing the blood vessels to thicken. Conversely, high blood pressure causes decreased delivery of insulin and glucose to the muscle cells, resulting in impaired glucose uptake (Salvetti et al., 1993). 

These are just a few of the mechanisms of how insulin resistance may be causing dementia. The more you read on insulin resistance, the more you learn just how horrible it is. For example, too much insulin will make you gain weight. Fat cells are like endocrine organs, meaning they can secrete signaling molecules. One of the molecules they secrete is cytokines, which cause inflammation. Inflammation causes further insulin resistance, which causes more inflammation, and the cycle repeats. This chronic systemic inflammation eventually reaches the brain. 

Another problem is that many people are insulin resistant and have not been diagnosed. If you are overweight and have high blood pressure, you are very likely to have insulin resistance. A few other signs of insulin resistance are dark patches of skin around the armpits and neck, and also skin tags which are little growths of skin. By the way, you don’t have to be overweight to be insulin resistant. You can be T.O.F.I., which stands for “thin on the outside, fat on the inside”. Fat can form around your organs. 

If you have some of these symptoms, you may want to speak to your physician about adopting a low carb, high fat diet. Also, you can order a self test kit to check your A1C. Find the test here, and use the code DPT20 for 20% off. 

References: 

Gasparini, L., Gouras, G. K., Wang, R., Gross, R. S., Beal, M. F., Greengard, P., & Xu, H. (2001). Stimulation of β-Amyloid Precursor Protein Trafficking by Insulin Reduces Intraneuronal β-Amyloid and Requires Mitogen-Activated Protein Kinase Signaling. The Journal of Neuroscience, 21(8), 2561–2570. https://doi.org/10.1523/jneurosci.21-08-02561.2001 

Salvetti, A., Brogi, G., Di Legge, V., & Bernini, G. P. (1993). The Inter-Relationship between Insulin Resistance and Hypertension. Drugs, 46(Supplement 2), 149–159. https://doi.org/10.2165/00003495-199300462-00024