In captivity, sugar glider nails must absolutely be maintained. This can be done by trimming or maintained by using sandpaper inserts in an Exercise Wheel.
The photo below uses a red line to indicate the portion of the nail that can be cut off. Make sure not to cut the quick or bleeding/pain may occur.
Sugar Glider's hind feet only have two nails that need to be cut. The hind thumbs lack nails. The back feet also have four fingers, two of which are fused together. These fused fingers have flimsy nails that are only used for grooming and they do not need to be trimmed.
Neglecting nails will minimally result in nail caps being painfully ripped off as shown below, but can also result in limbs being caught, twisted, mangled and even chewed off. Very easily an ungroomed nail caught in a pouch can be a death sentence for a little sugar glider.