For example, intranasal insulin reaches the cerebrospinal fluid within 10 min without altering the blood levels of insulin or glucose (Born et al., 2002) and has been shown to safely improve memory in healthy adults (160 IU/day) (Benedict et al., 2004), people with type-2-diabetes (40 IU/day) (Novak et al., 2022), and mild cognitive impairment or Alzheimer’s disease (20 or 40 IU/day) (Reger et al., 2006). Here, INS is linked to type 2 diabetes mellitus.