As mentioned in the OP; when you try to freeze a body, ice crystals will form among the cells. As the crystals expand, they will tear and rupture the cell walls. Glucose is the secret antifreeze that allows some organisms to go through this process without any issues. It works pretty much just like your car would; you put antifreeze in, and even though everything is frozen solid, liquid will still flow normally and allow your car to run. In the same way, glucose acts as an antifreeze and keeps the liquids in the body flowing despite the body being frozen. When it comes to humans though, the levels of glucose that certain frogs and fish use to undergo this process is enough to be fatal for any human being. From what I understand, it is totally possible for human beings to be frozen with cryogenics, and then revived. But it would take genetic engineering in order to make the human body capable of holding the high ratio of glucose required to survive the freezing.
