The global population of old people is due to skyrocket by mid-century, as people live longer and fertility rates go down. By 2050, one in every six people on earth will be over 65, according to estimates by ... and governments will have a hell of a time figuring out how to care for them. As people live longer, they will get more age-related diseases. Dementia cases globally are set to triple. Cancer rates are set to double. Diabetes in the U.S. may double or triple too, according to the Centers for Disease Control, hitting as many as one in every three adults.