In an animal model presenting both AD and T2D (by crossing APP/PS1 mice with db/db mice), in which T2D debuted at 4 weeks of age and AD (amyloid plaques) at 14 weeks of age, significant brain atrophy and tau pathology were detected in the cortex at 14 weeks and the hippocampus at 26 weeks, together with an increase in microglial activation. This evidence concerns the gene MAPT and type 2 diabetes mellitus.