Now I'll tell my counterpoint to gene's story. My left hand would become numb and tingly. New gloves did not help. I noticed that it even happened on slow uphills, when I was actually pulling on the bars. Then It started to happen when I was off the bike. I eventually went to the neurology department at the local hospital, I'm now waiting for their diagnosis.
My point is, there are non-glove possibilities, fit, size, and unrelated cause.
Good luck!