u/Mundane-Move4550

My 15 yo cat got diagnosed with diabetes a little under 2 years ago, and has been very difficult to get regulated ever since.
He was diagnosed with BG levels in the mid-high 500’s, but he has always responded well to insulin, meaning that even relatively low doses (according to vet, relatively low compared to his BG) brought his glucose down significantly. The most he has been on is 2 units twice a day, but that was too high a dose as his BG plummeted to below 40. Lowering to 1 unit (decreased in steps of 0.25) gave lows of around 100-125. Giving less his BG would stay too high (not going below 300). Unfortunately during those 2 years his BG always skyrocketed after the lowest point (which he reaches pretty early in a cycle, around 4-5 hours, until he was back to 400-500 at shot time. This never changed.

He’s on a low carb diet by the way, pate wet food with around 3-7% carbs depending on variety and low carb dry food (5% carbs, power of nature), the dry food is mostly for my other cat who NEEDS to have food available all day due to their medical issues.

I kept being told he was bouncing, to start from scratch from 0.5 units, keep the dose for a week or even 2 weeks, and increase in 0.25 steps. Didn’t work. Low doses meant he was in very high numbers constantly, until we got back to 1 unit and he would do his thing of lows around 100 and highs reaching 500. Very wild curves. And this cat does NOT show any behavioral symptoms of being either high or low except drinking and peeing a ton when his numbers are high. He’s very active no matter what his BG is. Those wild curves were day in day out for 1,5 years. Until now. Starting 3 weeks ago he suddenly started having lower BG levels at shot time. At first they were around 300, not spectacular for a diabetic cat, but for him they were. Gradually they kept getting lower, and now they are around 200 most days, and I’ve had to skip shots because he wasn’t going over 150 a couple times. And even without a shot for 24 hours he doesn’t go above 200.

I’ve been told by my vet that remission if it happens always happens in the first couple months, and certainly not after 2 years of poorly controlled diabetes. So I don’t dare to have much hope, but is it possible?

Oriental/British shorthair cross cat, age 17, neutered male, weight 9.9 lbs.
Medications: 37.5 mg phenobarbital twice daily

History: rescued as a kitten, got him as a foster placement after all his siblings died. Mom was one of many seized from a kitten/puppy mill and gave birth to him and his siblings (litter of 7) shortly after. They did well until about 6-7 weeks old, then the kittens were infected with FPV and he was the only one to survive (mom survived too, she never got it). He was also tested positive for toxoplasmosis. Sadly he didn’t survive without lasting effects, he has a (very) mild form of CH which when younger was mostly being a bit more ‘clumsy’, but he could run, climb, groom and feed himself without issues.
He has also suffered from poorly controlled epilepsy his whole life. We’ve tried different medications, levetiracetam (Keppra) which didn’t work too well for him, and phenobarbital which he is still on and has been for most of his life. He’s on a high dose, I know. But even with a VERY slow tapering to 25 mg (which is hard because they come in 25 mg pills and are difficult to divide into anything less than 1/2) he goes back to 2-3 seizures per month on average. With 37.5 he has had on average 1 seizure a month. His seizures are and always have been grand mals, but he is ‘fortunate’ to have a relatively short post-ictal phase and is back to normal (no confusion or altered mental state) within 30 minutes. We also tried a combination of a lower dose phenobarbital and Keppra, no succes, so we eventually opted for the high dose for seizure control, especially as he has a history of status epilepticus. The high dose does not seem to have a significant (or even noticeable) sedating effect on him. He has been on this dose for 10 years now.
He was also born with hypospadias which wasn’t discovered until age 5, for which he had a surgical correction (PU), and has a history of tooth resorption, all of his teeth have been extracted.
So… quite the medical history. I do want to say this cat is happy, he has always been and still is very playful and alert, he’s also an ‘easy’ and very friendly cat personality wise and does not seem to be in pain.
He has slightly elevated liver values, but they’ve been stable for over 10 years now and I’ve been told are probably a result of the phenobarbital. He has a CBC yearly and everything is currently fine (and always has been unless he had UTI’s or tooth issues) except for those slightly elevated liver values. Blood level for phenobarbital is also tested and is always slightly above what the vets consider therapeutic threshold (he’s at 45), but below that it’s more seizures. He’s never been seizure free for long periods, except for the past 7-8 months. Not a single seizure in 8 months for the first time in his life.

Now the current problem. Starting about 5-6 years ago I noticed him getting a bit more wobbly, hind end not really as steady as was normal for him. He was of course already getting a bit older by then, so I had him checked for arthritis and all that. No spinal issues, no significant joint degeneration, just ‘wobbly’. Vet said probably a combination of old age and not being able to compensate for the CH and other neuro problems anymore. Keep an eye on it.
It has progressively been getting worse over those 5-6 years. He can walk, he can run (actually running seems easier for him than walking), he still plays including playing tag with his adoptive brother. He can also jump (not very high but he has never been able to do that, couldn’t jump on a counter or table but was very good at pull ups if he could reach) and it doesn’t seem to be weakness so much but more a loss of coordination/ataxia. He also doesn’t seem to be in pain. Stands up easily either from sitting or laying down, but topples over if he takes a tight turn or when rubbing against objects or people. A slight push against his hind end and he’s on his butt. When grooming or scratching himself he falls backwards but just continues doing so lying on his back. So he doesn’t seem too bothered with it, but I’m worried, especially since I’ve been noticing how much worse it has gotten over the past year.
Vet now says that there might be neurologic changes in older age that make the phenobarbital more available(?) making it more effective, but thus also causing more side effects and thinks we should try to taper once more (which we haven’t done for 10 years). I don’t want him to have more seizures and I’m so happy he’s finally seizure free. I’m not assuming they’ll never return, but it’s been so nice for both him AND for me. He has fractured toes and teeth during seizures and sustained sprains etc, plus after a seizure he’s covered in pee and drool, as is my home.
Is what my vet thinks likely? That it’s side effects from the phenobarbital getting worse? Or even worse phenobarbital toxicity? Or could it just be worsening due to old age of his lifelong neurological issues?

Should I risk more seizures for a chance the ataxia improves? Or would other vets prefer seizure control over improvement of ataxia?
And how likely is it that his ataxia progresses to hind limb paralysis? The vet also said to watch for loss of bowel or bladder control, but that’s not an issue so far.
The ataxia so far doesn’t seem to bother him and he’s not in pain as far as I can tell. The seizures did off course bother him, so I’m kind of torn on what to do.