Dear Daveb45,
Strictly there are no vitimans that will lower B/G levels that I can think of. However a good diet should include Omega3 fish oils (eat Sardines/Mackerel/Salmon twice weekly) and in my own research I found that taking a Chromium suplements (200 micrograms daily) helped me as a Type 2 diabetic acheive normal B/G levels over a period of 12 years before eventually I was enevitably forced to go onto Metformin.
The Chromium suppliment may take a week or so before it cuts in, but I found it to help reduce my insulin resistance, and hence in my case gave me a much better overal B/G control.
Hope this info is of some use - Lazybones