In diabetes, insulin becomes less effective at controlling blood sugar levels. But insulin does a lot more than just control blood sugar; it is a “growth factor”. Neurons (brain cells) are very dependent on growth factors, and if they don’t get enough, they die.
The loss of insulin’s growth factor effects in the brain appear to make neurons vulnerable to stress and reduce the brain’s ability to repair damage that accumulates over time. (Neurons live as long as we do, so there is a lot of time for damage to accrue.)
When looking at brain tissue taken from deceased Alzheimer’s patients, researchers found that insulin lost its effectiveness as a growth factor, even in people who were not diabetic. This observation suggests that diabetes drugs might be an effective treatment for people with Alzheimer’s. Some experiments showed impressive results in animal studies, and several clinical trials have started.
Loss of insulin effects = insulin resistance