She could be tired, or spacing out, and I would get her blood sugar levels checked. How long ago was it that she was started on prednisone? What is her body weight, and her current readings? A few of them over the last few months would be good to know, too, as well as the exact dosage of prednisone (or is she on Prednisilone?) she is on, and her weight. If the pred is at a normal dosage for her weight, and not working as well anymore, you may have to add in another medication, Diazoxide, which the vet can prescribe if it is warranted. However, sometimes we just have ferrets who have off days, and even healthy ferrets can have reasons for just lying there, either they are bored, tired, cold, hot, etc. I don't believe that insulinoma itself causes any pain, however, it could cause nausea or general feelings of fatigue, I think, if meds are not doing their job. Laryssa [Posted in FML 6227]