worried

I always have in the back of my mind what is going on inside my veins when I am on a long run, and at the same time drinking sugary drinks and eating energy bars.

Surely insulin levels are all over the place?

... and is this a good thing for long term health?

I'm soon to enter an Ultra/mountain marathon. I'm thinking of eating all sorts of stuff to keep me going inc. sweets, mars bars, energy drinks etc etc.

Stupid question perhaps, but is all of this sugar good for you?