After trying many gel gloves that didn't help at all with numbness. I tried these:
http://www.bikebandit.com/aftermarket-parts/motorcycle-control-and-brake/grips-universal/grab-on-motorcycle-grip-covers
These helped prevent numbness quite a bit. The only downside is it makes the grip a bit larger. Felt weird at first, but I like now that I'm used to them.