Cat no longer responding to lantus. I'm panicking a bit about it.

Hi All,

My cat's name is Sufjan and he's ~7 years old. He weighs about 11 lbs and was diagnosed with diabetes in October 2020. We got him on the new, wet-food only diet and started him on insulin. After a month or so he went into remission. Unfortunately, while we were on vacation, he got into some dry food that was for the our other cat and relapsed. We began insulin again and quickly got him regulating in the 90-130 range. We steadied in on a dosage so I stopped checking his levels every day and switched to every few days. Eventually we started to notice that his levels were increasing. We tried upping the dose a bit but it wasn't very effective. Recently, his levels jumped to the lower 200s so we figured the lantus insulin was losing potency and that we needed new lantus. The one we were using was ~3 months old and was constantly refrigerated when not in use. While we waited for the new insulin, his levels got up to 300+ despite continued doses of ~2 units. His prior steady state had been ~1.5 units. We received the new insulin, now a lantus pen (to save money by not wasting all the extra fluid in the 10ml vial) and started at 1 unit, thinking that it would be more potent since it was new and didn't want to overdo the dosage. We have been using the same syringes to pull from the pen, not the mechanism itself, so it's not an administration issue. I've also tried rotating injection sites since i was mostly using the scruff up to this point. That hasn't appeared to make a difference. His levels actually continued to increase to ~330 so I upped the dosage to try to bring him down. Last few readings are below:

7/11 - 9am - 326 - administered 2 units
7/11 - 1pm - 331
7/11 - 6pm - 334
7/11 - 9pm - 305 - administered 2 unites
7/12 - 9am - 314 - administered ~2.3 units
7/12 - 12pm - 309
7/12 - 2pm - 304

So as you can see his levels won't budge. He seems in good spirits and is pretty active and curious, but is clearly peeing more again.

I've been doing more reading here and it seems overdoing the dosage could actually cause his levels to not come down, but i've never seen this kind of trend with him before. In the past when dialing in his dosage, we would do 2 units and his levels would clearly respond. Also, I might be being impatient? His levels just usually react very clearly to dosage and now it seems like he's not responding at all.

Now I am second guessing if anything was wrong with the old lantus after all or if his levels were just increasing for unrelated reasons. I've read that this can happen if he's fighting other health problems, but i haven't noticed any changes in behavior from him that would corelate. I've already called the vet, but she's out of office today. We'll chat tomorrow and see if she thinks she should check him for other issues. In the meantime I'm kinda panicking that he has some underlying other illness and will have to be put down or something. He's not the healthiest cat, as he seems to have some level of arthritis and is a loud breather so i really worry about him. Thanks in advance for the help.

 

I'm a little confused. How long has Sufjan been on Lantus this time around? And, how long has he been at this dose? Would it be possible for you to provide more information on your spreadsheet if you have it?

Lantus is a depot insulin. As such, you need to hold the dose for several cycles (at least 3 days/6cycles) in order for the insulin depot to catch up with the dose. It is very different than other insulins in that each dose overlaps with the previous dose. If you change doses too rapidly, you end up with wonky numbers.

Without seeing any history, it's hard to know if you have been holding the dose for overly long. Staying at the same dose when it's not brining numbers down can cause glucose toxicity -- your cat treats the higher numbers as the new "normal."

One other bit of information is that it is typically harder to get a cat back into remission a second or third time. One of the issues that often throws a cat out of remission is a dental problem. You may need to get your cat's teeth checked to make sure there's no inflammation or infection present.

 

He's been on lantus again since April 11. I have a long spreadsheet of my own, but he was averaging 90-140 at 1.5u for a solid month and a half once we hit steady. His PMPS just 30 minutes ago actually came down to 258, so it looks like that depot you mentioned is building up. I knew it was a smoother insulin but didn't fully grasp the depot element till you explained it. So I guess I just need to hold steady for awhile and see where it lands. Thanks for the explanation. It and the most recent number have put me at ease.

Also, I'm not even really hoping for remission. I understand it's much less likely the second time around. I just want him in a good range and if remission happens, great.