INS and type 2 diabetes mellitus: In line with this, the roles of metformin on the reduction of insulin resistance (Figure 1), plasma fasting insulin levels, glucose, lipid and protein synthesis, and cell growth, also stimulating fatty acid oxidation (68–70), (most of them common features to T2D and AD and involving LKB1-induced AMPK activation) rendered this drug a promising therapeutic approach also against AD (Figure 1) (62, 63).