after i got diagnosed with hyopglycemia last year i got sent to a nutritionist. here's the gist of what i was told:

avoid sugar.
canned soup can be good of it's low in sodium.
cheese is under-rated. it makes a good snack b/c it fills you up quickly and has a lot of protien. soy nuts (eps. roasted and salted) are awesome! and i'm really picky but i love 'em.
can't say enough about fresh fruits and veggies.
avoid all kinds of white bread- loaves, beagles, ect.- always go whole grain when you can.
don't even go near the snack foods like chips or soda.