There has been much debate here on the need of the brain for glucose and how that relates to fats.
Triglycerides are a chemical storage system for fats. Fats are stored in threes a bit like toast in a rack. The rack is glycerol.
Wikipedia say that the backbone of triglycerides glycerol can be converted to glucose.
RB
http://en.wikipedia.org/wiki/Triglyceride