Sugar Gliders?

Ok; dogs cats hamsters & ferrets I am really good with as well as other animals but when it comes to Sugargliders I am clueless - me & my friend always argued who was better; my ferret Rudy or her sugar glider Skuttle; I was never really interested in them therefore I dont know that much about them; anyway she hasnt had him for all that long maybe about 3 years or so & this morning she woke up & he was dead. I know that she took good care of him & everything; she doesnt know why he died so if anyone has any information about their usual life span or anything that might have contributed please answer; thanks