Very High Lantus doses in a cat with Acromegaly

Apologies as this is a crosspost from the Lantus forum. I did not see there was a more specialist venue.

I am interested in other peoples experience with Insulin resistance due to Acromegaly at very high doses.
Hopefully the question will help others on the same path as well as I have done a quite a bit of research.

The cat in question is a 13 year old neutered male and 20 months in from DM diagnosis with a follow up confirming IGF-1 test. BS at diagnosis was around 450 with PU/PD.

Elected not to attempt surgery or radiotherapy as the results are marginal and no nearby center and just treat the DM. UC Davis were negative on surgery and neutral on radiation.

He has been under specialist vet care from experts in the disease and mostly doing ok. Close to normal metabolic panel with a minor heart murmur. He is already beyond the mean survival rates from aggressive treatment. One happy cat and weight stable or increasing. A lot of snoring as expected but still quite active.

The Lantus doses, are getting very high to get any kind of control and have increased progressively as per the usual progression. Currently 35U/BID so 70U a day of Lantus with a nadir around 350. I know this is going to sound impossible for anyone with a cat with simple DM! Confirmed with Abbot Libre CGM and AlphaTRAK 2 with feline calibration. No adverse reactions.

Probably going to need 40U BID/80U a day to get to a 250 BS target.

Does anyone have experience at these very high doses? Specialist vet say he has seen even higher doses (90U) but the caution is fluctuation in the IGF1 as the tumor gets unstable, reducing the insulin resistance, which at this dose would not be good! There is not much data.

Obviously all cats are different but would be very interested in anyone else who has been down this path, especially the instability from parts of the tumor losing blood supply and potential Hypoglycemia.

Thanks!

 

I've answered on your post in the Lantus/Basaglar/Levemir forum: https://felinediabetes.com/FDMB/thr...-at-very-high-doses-others-experience.248585/

Where do you live? I drove 3 days to Colorado State University for radiation therapy. Neko lived about 5 years with acromegaly, though she didn't get to as high as dose. I don't consider that a marginal result. She had a much better and longer quality of life with radiation therapy. It's fine that you are just treating the DM, we've had plenty of people do just that, as the surgery and now the radiation therapy have been priced out of range of many. I was lucky that is was half the price it is now. You might want to consider trying the medication called cabergoline. It's a daily dosed med that seems to help acro symptoms and people have seen some reduction in dose.

Most of us target much lower nadirs. The goal is to keep the cat under renal threshold as much as possible, so well under 250. Have you considered a switch to Levemir insulin? For many cats it seems to have longer duration at higher doses. And the Lantus base can sting at higher doses. Levemir has similar action to Lantus, but without the sting.

 

My MurrFee (GA) was up to about 50 units BID (25 Levemir and 25 N). That controlled BGs under 200-250) all the time. At the end he would not eat and was lethargic (no ketones though)

 

Thanks for your inputs!

Agreed on wanting to try and get down down to lower numbers perhaps 150 but obviously these are very high doses and any variations in hormone secretion would not be good. When he was at 10U or so BID with an Abbot CGM it was pretty easy to get to a nadir of 100 or even cautiously lower.

I will look at the alternate insulins but the cat has zero sting reaction from the shot currently.

UC Davis is about 2 hrs away but the associate prof there who was doing the surgical study was a bit negative on the radiation. A lot of trips for the fractionated dose approach too and as you mention now very expensive. There is pretty limited trial data with control groups as you know.

I did talk to Dr Bruyette, who seems to be one of the experts in the field and he was a bit negative that the Cabergoline did much. As you mention it might be worth it at these doses if only to reduce the amount of insulin.

Thanks again!

 

There have only been two formal studies on cabergoline, both on tiny numbers of cats. We've got more data here. Of the two studies, the one in England was just a trial and said more research was needed. The study in South America got to the point that it's now what they recommend for all acros and they've now studied I think close to 50 cats. Unfortunately, no published research which is what vets look for. In addition to reducing dose, for most it seems to reduce some of the impacts of the growth hormone, such as the snoring. Best thing about cabergoline, it's cheap and easy to give at home. We've seen three cats go off of insulin while taking it.

Now that I have a little time, I'm going to link a couple spreadsheets for you, of fairly well regulated cats on much higher doses. Crystal maxed out at 60 units of Levemir and 26 units of R. When her dose started coming down, Suki just stopped giving R or greatly reduced it. Here is Crystal's spreadsheet. She had no treatment but insulin. She was in France where nothing was locally available. Second kitty is Pig. He has SRT at Washington State University. His caregiver drove across the country to WSU cause SRT was so much cheaper there. Unfortunately they have stopped offering it there. Pig got up to 59 units of Levemir in 2018 and seemed to need less than 5 units of R. Here is Pig's spreadsheet. As I said before, those are unusual cases to see that high a dose. Mid 30's is more common. These are all people who have home tested several times a day, and thus are able to aim for nadirs closer to 70, which was my goal too. If you are home testing regularly, the growth hormone changes are not sudden enough to make that goal dangerous.

Stereotactic radiation therapy is 2 to 4 consecutive days of treatment, which is why it made sense for me to travel and state in Fort Collins to get the treatment done at CSU. Neko got treatment during the day, and came back to the hotel at night. There are quite a few papers that talk about SRT.