The seminal fluid contains fructose as the main energy source for the sperm and not glucose.
Why is fructose and not glucose the primary energy source for these sperm, since glucose is the preferred energy source for most other tissues?
I have been searching this for a while and I got something of an answer, which I am posting below.
1) Quoting the book here,
Thus, to avoid other competitive bacteria and cells from utilising the energy source of sperm, fructose is used as the energy source since the bacteria prefer glucose.
2)Another reason is that the metabolism of sorbitol into fructose is energetically efficient way (no ATP required) as compared to glycolytic conversion of glucose into fructose(G$\rightarrow$G6P$\rightarrow$F6P$\rightarrow$F). Tapping the polyol pathway is energetically preferred to metabolizing fructose produced during glycolysis.This is only to show the possible evolution of the polyol pathway once the advantage of using fructose as the energy source was established. It does not explain why the fructose was advantageuos but just that if it was advantageous, the semen-producers would develop the currently existing machinery to produce fructose as the exclusive source of energy.
Hence, sperms (seminal secretion) contains fructose as the primary energy source and not glucose.