Some people are okay if they eat potatoes and others go sky high if they eat anything made from a potato in it. I mean, yes, both parties have their blood glucose
go up, but one will go up higher than the other. Same with rice, apples, bananas, candy, and so on. Just like meds, food is different for everyone. No one knows why.
Stress also effects diabetes and blood glucose levels. My only suggestion is that something about potatoes has that effect on you. Like eating a ton of sugar.