hmmm.. never even thought about this. it would depend on the stim you are using... list the ingredients and see whats in it
i know a lot of things out there screw with blood sugar levels that you wouldn't expect. many supplements, protein bars, and energy drinks are full of sugar for example.. i see some guys drinking gatorade or other scam sports drinks, that will send your blood sugar sky high.
i know that supplements that have xylitol will drop your blood sugar and are bad ideas before a workout. it will kill your energy
I like to have a raw sweet potato before a workout. its easy to digest, its got a shitload of nutrients and vitamins, and it will give you just enough energy to have a strong workout WITHOUT spiking your blood sugar