I had the exact same reaction.

I did measure my BG a few times; it didn't spike, but it did rise 2-3 times more than the theoretical net carbs would predict. I routinely doubled their listed "net carb" counts in my daily accounting, but that didn't help. I quit buying them ~15 yrs ago, because of the cravings that take away my control, and if I do not feel in control of my eating, I cannot stay on the diet that works for me for life. I've also cut out milk proteins, legumes and all grains for the same reasons. It is not just BG that you have to worry about as foods contain casomorphins, gluten & gliadin exorphins and affect other hormones besides insulin. But you do need to figure out which foods work for you and which don't. I'm not perfect and do occasionally eat the foods I've cut, but the cravings for junk will start 45-60 minutes later and I have to nip these excursions in the bud or the urge to binge is heightened.