I did not mean not to use gloves as well. I meant the insoles could be extra padding. One could cover them before attaching them to the grip. You could make the cover removable so it could be washed and kept clean. The cover would keep it from looking tacky as well.
I myself may have to do this if I have any problems with my thumb once I start riding longer distances. Again is only a suggestion.

Justin, I never said do not wear gloves. I wear gloves no matter the weather as well.
The topic is, finding a solution to the vibration she is having from the
grips. I came up with what I belive to be an inexpensive as well as clever
idea. If you thought I said not to wear hand proteciton then, you misread what I wrote. kim

Try a pair of these grips.  I used them for years on an R65 with S bars and no end weights.  They work because the curve is more natural for the hand.

http://www.lowbrowcustoms.com/index.php?l=product_detail&p=292

I would guess that this is an operator issue rather than a MC issue. However on long rides, a lot of riders start feeling the tingle.

On long rides shaking out your arms or letting them rest really helps. Some riders do this going down the road easy on the left, not so much without some type of throttle control (cruise or lock) on the right.

For me this issue is reduced the more I ride. If all I'm doing is commuting (20 m/d) when I get out and ride a couple of hours my thumbs will tingle. If I'm riding over 100 m/d then I don't notice it at all.

Something else that seems to make it go away, if I'm lifting weights and working on hand strength.