i was out on the GTR on saturday & while on the bike i had pins & needles in both hand's that bad my hands went numb, i used to get it mainly in one hand, not both, i tried those sponge sleeves in the past, which you pull over the grip's, not sure what they are called, they made the grip's to wide. is there away of preventing this.....
It might sound silly, but it works for me :- Don't grip the bars too tight. Consciously relax your grip now and again