Vitamin C

Hello all:
I am new here and eager to get some feedback and help with health questions.
I am diabetic and somewhat allergic to vitamin C but want to try using it anyway to deal with some health issues.
My basic question is:
What would be a good, digestible, easy to use form of vitamin C (pills, powder, liquid, etc.) and where can I get it. I'm in the L.A. area and have access to many good health food stores or the web. I'd appreciate any personal experience anyone can offer for finding and using a good quality and digestible form of vitamin C.
There's some other stuff I wish to ask about but not just now.
Thanks in advance for any leads or feedback anyone wishes to offer.
:)
Irene