Levemir has a neutral ph base. Lantus is slightly acidic. Punkin stayed on Lantus and he peaked at 15.5u per shot before being treated for acromegaly.
Levemir and Lantus are both great insulins for cats. Prozinc is good too, but it doesn't last quite as long in the body as Lantus and Levemir. Especially with high dose cats, lasting longer is a huge asset. I wouldn't go from an L insulin to ProZinc. There's nothing bad about ProZinc, but most people switch from ProZinc to an L insulin because they simply last longer in the body. We've been told that Lantus and Lev are similar in duration (how long they last) but given by the spreadsheets I've seen, I can't help but think that Levemir lasts longer. Cats do vary in how long a short lasts (its duration) before it wears off.
I would've suggested you stick with the Lantus and work on dosing more aggressively. Usually we suggest giving an insulin 6 months with good dosing before deciding it doesn't work. All of them will work but you have to get to the right dose. If you're not seeing a lot of blue, increase every 6 cycles following the guidelines below. Look at the nadirs over the past 6 cycles, decide if they are mostly over 200 or under 200, and if they are over 200 increase by 0.5u. Once you've passed about 5u we suggest moving to 0.5u increases instead. Think in terms of the % of increase. On a cat getting 1.0u, an increase of 0.25u is 25%. When you have a bigger dose, you need bigger increase increments to make a difference. Holding a dose too long is a mistake - if the dose isn't getting the cat into good numbers, that dose allows
Glucose Toxicity to build up. Then you need even MORE insulin to bring them down.
Increasing the dose:
- Hold the dose for 3 - 5 days (6 - 10 consecutive cycles) if nadirs are less than 200 before increasing the dose by 0.25 unit.
- if your cat is new to numbers under 200, it is recommended to hold the dose for at least 8-10 cycles before increasing.
- when your cat starts to see nadirs under 100, hold the dose for at least 10 cycles before increasing.
- After 3 days (6 consecutive cycles)... if nadirs are greater than 200, but less than 300 increase the dose by 0.25 unit.
- After 3 days (6 consecutive cycles)... if nadirs are greater than 300 increase the dose by 0.5 unit.
It might be good to get him tested for acromegaly and iaa. Acromegaly is more common with the latest research indicating it affects 1 in 3-4 diabetic cats. We see a LOT of kitties whose diabetes was caused by acromegaly. We are seeing more iaa kitties too. The "look" of iaa is that initially a dose might get a cat into lower numbers, but then it's like the dose "goes stale" (Wendy's great description) and then the dose won't get them into good numbers again. I'm not really seeing that on Otto's ss, but the incremental cost of getting the iaa done in addition to the acro is only something like $15. It's well worth it to get both tests done at the same time.
edited to add: HEre's the
Where Can I Find? post. There is a description of how Lantus & Lev each work in several of the stickies at the top. Try the one on the Insulin Depot.