Be aware that this study comes from Colorado State University. Here is a quote from their web site on diabetes management. After you have read it ask yourself what credibility they have.

Carbohydrate. The percentage of carbohydrate in the diet also will vary according to individual needs and goals. In general, 50 to 60 percent of total caloric intake should come from carbohydrates. Important sources of carbohydrates include breads, cereals, grains, pasta, fruits and vegetables. Again, carbohydrates may be reduced in some people's diets to address individual problems.
Here is the full article.
http://www.ext.colostate.edu/pubs/foodnut/09334.html