I apologize that no one has responded to your question sooner. Different experts come online at various times. I just came online and saw your question. My name is ***** ***** I’m a biologist with a special interest in small animal health. I'm sorry to hear that you are having to make the most difficult decision we face as pet owners.
it all comes down to Willie's quality of life. Once an animal becomes lethargic with a chronic disease, it often means there is pain or at least discomfort, and he may not be getting a lot of enjoyment out of life either. I can assure you that if you decide to let him go now, no fellow animal lover would think you have done it too early. You know with certainty that he is not going to get any better, but will only continue the gradual decline that insulinoma eventually causes.. Here is a site that may help you with the decision:
This is a decision only you can make. It's normal to feel guilty and unsure no matter which way you decide to go - Am I causing him to suffer longer by not euthanizing him? Am I taking away some enjoyment of life by doing it now? There's no doubt that it's a horrible decision to make. You can look at how much enjoyment Willie gets from eating. Does he eat with gusto, or pick at his food? When he's asleep, does he seem comfortable, or does he shift positions a lot as if he can't get comfortable? Eating and restful sleep are often the last remaining things a pet may still enjoy, and if he's not getting any comfort or pleasure from them, then his life doesn't have much quality any more.
I can't make the decision for you, but only give you some things to consider. If it would help you to talk some more about this, just click on REPLY and post (no additional charge). I've been through this more than once, so I know how painful it is. If I can help you further in any way, let me know.