Unfortunately there isn’t a lot of knowledge in what to do if your glider gets sick.
Luckily gliders are known for having relatively good health. However, if something occurs here are some tips:
If your glider is slow moving and lethargic he/she may be too cold. In a sugar glidersactive area they are used to being in 90 degree wether. Try to wrap them up in a heating pad. You should see them start to regain energy.
If your glider is underweight you can tell by being able to clearly feel the bones of their back. Increase the amount of protein and overall nutrients in their diet and watch their weight closely for a few weeks.
If your glider becomes depressed you may want to get them a friend. If they are depressed due to loosing a friend the best thing you can do is get them another one ASAP or they will continue to become more and more lonely.
For constipation ask your vet for a laxative and dab it on a toothpick and let your glider lick it off.
If your glider is experiencing diarrhea use a clear flavored pedialyte for 24 hours with nothing else. No water, food, or treats. This usually does the trick.
If your glider is hurt or having seriously unusual behavior please to hesitate to take it to a veterinarian. I use Avian & Exotic Animal Clinic in Indianapolis. When finding a vet for your glider it is important to find someone as close as possible. Usually they are only seen by exotic vets but try calling your local vet to see if they will see them because some will.