The best thing is simply to take a multivitamin that is specially formulated for diabetics rather than trying to create your own "cocktail" .   They balance all the vitamins, minerals and antioxidants along with the specialty supplements you don't find in "general Market" vitamins like Centrum (like alpha lipoic acid).   I find that the multi's in the vitamin section of most drugstores just don't cut it.   I buy mine at Walgreens near the glucose tabs and lancets.  Its in a bright green and yellow box, and I'm pretty sure its called Multibetic.   I really like that its the most potent formula I can find and yet the pills are small and easy to swallow.