Hi,
For the protocol "Plasmid DNA Extraction from E. coli Using Alkaline Lysis Method", Glucose is added (in resuspension solution) to make the solution isotonic. In fact, isotonicity is not required for bacteria with cell walls (i.e. E. coli) because bacteria with cell walls can withstand wide range of solution concentration. Thus, glucose may not have to be included in the resuspension buffer. I never tried the one without glucose, though. So, please share your experience with us if you try it without glucose.
Good luck,
Fanglian