However, the ability of the brain to adapt to low glucose in insulin-injecting diabetes patients (Maran et al., 2000), to low oxygen in people at high altitude (Hochachka et al., 1996) and increased ketone body in diet (Roy et al., 2015; Murray et al., 2016) suggests that the brain makes use of more than one mechanism to acquire energy. Here, INS is linked to diabetes mellitus.