Add some butter to your whole-grain-bread, like I do, and you'll end up with some good calories... and I always hated counting those calories that make a bread worth be eaten.
Bread is chock full of bioavailable calories to start with, adding a smear of butter on top doesn't really change it that much.
That fat blunts the insulin response.
I've always read that the insulin response to fats + carbs is higher than carbs alone.
Eh, I don't think that is the case. Ice cream has a much lower glycemic index than bread for example.
Or just take r-lipoic acid after/with glucose heavy food consumption. It'll help prevent and or lessen the spike. Diabetics use it to control their glucose levels. It can significantly push that down. I'm not seriously suggesting this of course, however it does work.
Bread is nothing without butter.
Exception: freshly baked baguette or ciabatta.
I've turned to hummus and veggies to cut out butter and cheese completely.