For some good reading on the subject, check out Ray Peat's article "Glycemia, starch, and sugar in context" at http://raypeat.com/articles/articles/glycemia.shtml.

While not specifically about sugars, the Weston Price book is a good read about traditional diets as well: http://www.amazon.com/Nutrition-Physical-Degeneration-Weston....

Food, Inc. is also available on netflix streaming. Quite a good documentary.