Potatoes are my worst enemy!
The highest spikes I have recorded are in high double figures because of spuds, that is from normal levels after an hour or so.
Potatoes contains starch, which is high GI carbs.
Then again it is dependent on how old the potato is, how it is cooked, type of potato, what you eat with them.
Some people are intolerant to gluten, so what replaces the gluten in gluten free foods?
Potatoes starch. Which is very high in carbs because it is concentrated.