I haven't tried this yet myself, but someone in a diabetes group I belong to gave this tip, which she uses all the time.
She said that whenever she makes anything with flour she adds two or three heaping tablespoons of Benefiber to it. It increases the total fiber in the recipe, and she said it has helped keep her blood glucose levels from going up. She also said that if she is making a dark bread she adds apple pectin along with the Benefiber. She said that even brownies don't raise her bg levels now.