What I have learned when studying and researching into the diets
is that the gliders in the wild eat many gums and saps. These gums and saps are high in complex carbohydrates. Because we do not have the same types or amounts of saps and gums that sugar gliders eat in the wild available to us,we have replaced it with fruits and vegetables.
I'm also not sure that I agree with you on the idea that a captive sugar glider would have different dietary needs than a wild one.
Captive animals do indeed have a different dietary need than wild animals as their whole digestive system is different. In such ways as the metabolism is affected as with more room to glide, run from those wanting to eat them for dinner etc, the adrenaline and metabolism would kick into high gear, whereas in a cage, they dont have the same space, stressors.
Much like a couch potato digests foods differently than lets say a runner. Although the same types of food may be consumed, the runner is going to burn off and digest foods faster and better than a couch potato.