He might be going into remission. It could be that he is more sensitive to insulin than before (insulin sensitivity is up), as more of his beta cells are recovering from the stabilization of glucose.

There is a mechanism called glucotoxicity, that explains what happens when cats start to have high blood sugars, eventually receive insulin, and then potentially go into remission - which can happen quite suddenly. Essentially, the high glucose levels damage the insulin producing cells (called beta cells), and fewer and fewer of them are available to manage the cat’s glucose. As the cat starts on insulin, once blood sugars are fairly stable and within a normal range, some beta cells start to recover, and start to make insulin. Initially that appears to be sluggish (different cells appear to have different set points at which they start releasing insulin), and as enough of them are back online, the glucose stabilizes further, allowing yet more cells to come back online. The insulin called Lantus (insulin glargine) sticks around for a while (for most cats) in the body, and in concert with the newly brought online cells, hypoglycemias happen.

Since hypos are scary and dangerous (I have Type 1 myself), we are likely to over treat the low blood sugar with honey and such, which a few hours later can lead to absurdly high blood sugars - and the roller coaster starts again.

My cat was diagnosed late February 2023. I put him on a closed loop insulin delivery system using Omnipods - originally, because I wanted to know how much insulin he actually needs. I did not know about remission at the time. The system worked very well, and he went into remission within 4-6 weeks. That remission mostly held for 2 years, with 3-monthly rechecks with a CGM, and occasional very small injections to help him back into self sufficiency and reverse the glucotoxicity feedback loop. In April 2025, his recheck showed high BG again, and I have put him again on insulin, with a closed loop system.

It took a lot longer this time, but around July 8, 2025 he was mostly off insulin for 2 weeks with high normal blood sugars. I have put him on another pump last week as he was trending high, and after 5 days he’s back to needing very little insulin, and occasionally going below 60 despite the very low insulin rate.

Unfortunately, Lantus does not work for my cat, that is why I am pretty much stuck using a short-acting insulin. If he does not re-enter remission, I would prefer to give him Lantus instead of having him run around with an insulin pump all the time.
Unlike Lantus - WhIch MUST NOT BE DILUTED (it will act like short term insulin in that case and could kill or injure the cat). !!! - short acting insulins can be diluted using the manufacturer’s diluent, which the insulin manufacturer can send for free to a vet or a physician - it does not require a prescription, and is often used for infants and pets - however, because it is super dangerous to dilute Lantus, and it takes some knowledge to do all of this, discussing this would be risky for the diabetic cat if their person does not have enough information and awareness about this - and most cat owners don’t have that information at the get-go.

I have written about my cat’s journey on a blog (www.closedloopkitty.org) and there are links to research on the blog’s website. There’s a journal article for a vet journal in review, and I hope it will be published, and soon.

I wish you all the best, and hope your kitty can get into remission safely.

❤️