The idea that whole grains don't raise blood sugar as much as refined grains is another myth beloved by nutritionists. It hasn't held up to research. And years ago when it was discussed on the old diabetes newsgroup many people reported that the whole grains raised their blood sugar just as much as the refined ones. That was certainly my experience.
People who have normal insulin production will see a difference, because their insulin will mop up glucose from slower digesting carbs so they don't show up in the blood but people with diabetes no longer secrete much insulin or if they do, it isn't effective due to problems with the liver and muscles taking it up. So for them, it all boils down to total carbs, rather than what kind of carbs.
I personally like whole grains better than refined, much of the time, but I limit the portion sizes drastically, as I can't eat more than 1 slice of bread or 1/2 of a small potato without blood sugar problems. The amount of pasta that fits my metabolic ability to handle it is so small as to be not worth eating. So I don't eat it.