Is the main provider of energy for the brain and nervous system.

Glucose is the main provider of energy for the brain and the nervous system. Because the brain is so rich in nerve cells, or neurons, it is the most energy demanding organ, using one half of all the sugar energy in the body. Brain functions such as memory, thinking and learning are closely linked to glucose levels and how efficiently the brain uses this fuel source. 

Yes he thought they should be left to chance why, because he thought that was the best thing to do