**5. Type 3 diabetes**

There may be a connection between T2D and Alzheimer's disease (AD). Indeed, it has been proposed that AD is actually a form of DM termed type 3 (T3D). Globally, the epidemic of T2D and the possibility of it contributing to the risk of AD have become a paramount health concern.

The hypothesis is that T3D corresponds to chronic insulin resistance plus an insulin-deficient state that is mostly confined to the brain [11, 12]. A deficit in glucose utilization is observed, which ultimately leads to cognitive dysfunction. Over time T3D steadily destroys cerebral functions due to insulin imbalance. Thus, the central nervous system develops insulin resistance, which leads to AD [13].
