Hey. I have an old cat. He is almost 15 years old. One month ago he was diagnosed with diabetes. He is not responding to insulin. I have tried mixtard up to 5 unites twice a day then moved to caninsulin 4 units twice a day. He never drops below 400. He does not respond to an increase in doze or change of insulin. Nothing! And I am giving him insulin for over a mobth. I have no idea what to do... Has anybody experienced anything like this? Thank you