The Agaricus Mushroom is reported to help significantly with blood Sugar control.
Cinnamon extract (CinSulin(r)) is also helpful.
Biotin is also important and should not be overlooked (quote from a web reference):
"In one study, blood biotin levels were significantly lower in 43 patients with diabetes than in non-diabetics, and lower blood Sugar levels were associated with higher blood biotin levels. After one month of biotin supplementation (9 mg/day) blood Sugar levels decreased by an average of 45%"