I managed to contact a Veterinarian and Researcher that works at the University Animal Hospital in Uppsala in Sweden. She was very kind and looked at Severino spreadsheet, at the veterinarian answer, and gave me her veterinarian point of view for free. That´s why I have shot at 5
"Wise to reduce the dose. Does not look like he should have more than 0.5 IU. Maybe 0.25 may be enough, but preferably you should not change the dose more often than once a week, so it would give a few more days at the current dose. Since he has not been on insulin for so long, I would not give anything if he has below 5 in glucose. If he is alert and the meter shows 3.8, I would not do anything but have a little extra control over the next few hours. If you are still worried or if you can not keep him under supervision, it is not wrong to give a little extra food. If it continues like this, I think there is a good chance that he will be insulin-free! I think you can measure glucose morning and evening before giving insulin and then make a curve when he has been on the new dose for a week. Then measure every two hours and as you approach nadir you can measure even a little more often. You have an occasion where he goes from 4 something up to 16 from one hour to the next. Could be a recoil. If he has more like this or is often so low below 4, I would try to lower to 0.25 IU. You are doing great!"
What is 5 in a pet-meter in a human meter?