In the wild, a gliders diet consists of fruit, tree sap, nectars, insects, bird eggs, and even small lizards or rodents. There are a lot of web sites out there with specific diets for gliders, some are from zoos and breeders. Your pet also needs vitamins, especially calcium. A lack of calcium can cause paralysis in their back legs. Foods high in phosphorus will deplete calcium.
Corn is really high in phosphorus.
I have had my glider for 3 years. I took my glider to a vet that specializes in exotics, and he said she seemed pretty healthy. I feed mine fruits and vegetables, usually fresh, but sometimes frozen. For protein I give her cooked unseasoned chicken, hard boiled and scrambled eggs, meal worms, crickets, and baby food. Check all food for added colors or preservatives - avoid them.