MAPT and type 2 diabetes mellitus: In the study of Rezaei et al. (2023), the T2DM rats showed decreased serum and hippocampal levels of insulin and adiponectin at baseline, as well as decreased levels of insulin receptors, adiponectin receptors and AMPK in the hippocampus, and increased hippocampal GSK3β and hyperphosphorylated tau.