great to hear from you!
The T4 is a little high for an old kitty, even if in the normal range. I would check it again.If over 1/2 of the normal, I would ask for a T4 ED.
Potassium is good, but it would be good to know what it is now.
Vitamin B12 can help some diabetes kitty that have polyneuropathy (walking low on hind legs). It may take 45 days to control the condition sometimes. How many days are we in?
Very important, those little ones tend to have urinary infections with no or very little symptoms. Would be good to have a urine culture done to be on the safe side.
As for weight loss, let's look at the categories:
1- Not good diabetes control
2- Other disease process going on
3- Not eating enough.
Diet is really important. a low carbohydrate diet like M/D canned (not the dry) is a good start. But high in protein.
I would like to know how his kidney values are right now. If near normal, discuss with your veterinarian, if it is better to tackle the DM because if the weight loss is from the diabetes, we won't won't have much Fluffy left soon! If M/D does not work, i can find out a list of low card diet on the market. Yes lot's of protein, but remember kidney first or diabetes? Or try to change insulin first. If high carb diet, wait for possibly high blood sugar numbers in between insulin injections.
As for insulin, Vetsulin will usually have its peak activity about 4 hours after injection. it is an intermediate type of insulin.
We are trying have 75% of the time the BG (blood glucose) between 80 and 300. Moderately to severe diabetic cat will not be able to stay 100% of the time in this range.
10% of kitties with diabetes can have some kidney inflammation due to their condition.
What is good is that Fluffy is responding to insulin! Good news!
How about another insulin? yes, you can try glargine insulin Sanofi, Adventis). It is a human insulin used for 24 hour control. In cats, twice daily is better. You need to start at the lowest dosage to avoid low blood sugar. Since this insulin is a long acting type, it might be all that is needed to control his diabetes. But diet maybe important. Also keep in mind that a small amount of cats, can get ride of diabetes. That is why i still think you should learn to get blood sugar reading at home. It is now very common to do it. When stressed, a cat's sugar will go up very, very high!
Let me know what you think.
Here are sites about testing your kitty, problem regulating kitties.
Make sure you copy the link, then add the = at the end of it. Let me know if you have problem getting into those links.