Switching from Caninsulin to Lantus

[RosettaSpice]

Our guy (14.5 y) has been on caninsulin since October 10 2025 first was 2 units then increased to 2.5 because of his high numbers. His numbers have been all over the place, some days being really good with 7/mmol at peak and 21.9/mmol at the highest just before a dose. We have both Lantus and a box of U-100 syringes coming and will be testing every 2 hours on Friday.

Do we give him the same dose as his Caninsulin?

Do we have to convert it to the new measurement for the U-100 syringe?

Any other suggestions or comments would be greatly appreciated!

 

[CORKY]

Welcome to FDMB
Caninsulin is a dog insulin this is can be a reason of BG numbers all over the place, this insulin hits hard and fast in a cat, so Is good you are switching to Lantus, Are you home testing or are you doing the curve at the vet? what are you feeding? diabetic cats need to have a diet of wet can or raw foods between 0-10% should be on a schedule, not grazing, kibbles are between 20-30% carbs, so if are feeding dry food, this can also be the reason, I do not give dosing advice, but I will tag a couple of members that can assist you with Lantus dosing, We are here for you.
@Wendy&Neko
@Sienne and Gabby (GA)

 

[RosettaSpice]

Thanks!

He’s on exclusively on wet food diet for diabetic cats (under 10% carbs) we do home testing for his glucose levels.

Our vet wanted him to stay on caninuslin and up the dose even more. We’ve decided to use Lantus on our own. Just looking for some advice on what to expect and how to accurately dose him at home, any suggestions or comments are appreciated!

 

[Sienne and Gabby (GA)]

You can make a unit-to-unit switch from Caninsulin to Lantus. Some members prefer to slightly reduce the dose if starting a new insulin. What is the current dose of insulin you're giving your cat?

It would be helpful for us to see a week or two of your home testing data. This is a link to a post on helping us to help you. It has instructions for setting up a spreadsheet. This will allow you to track your cat's progress and it will allow us to follow along as well.

 

[CORKY]

which wet food diet for diabetic? are you sure is 10%?, 99.9% of all supposed diet for diabetic or "prescribed" are very high in carbs , wet or dry, did you get it from the vet? this can be a reason of the BG being all over the place humans just regulate their diabetes with low carb foods, and insulin, can you post what is the name of the food and I can find out the carb content for you

 

[RosettaSpice]

You can make a unit-to-unit switch from Caninsulin to Lantus. Some members prefer to slightly reduce the dose if starting a new insulin. What is the current dose of insulin you're giving your cat?

It would be helpful for us to see a week or two of your home testing data. This is a link to a post on helping us to help you. It has instructions for setting up a spreadsheet. This will allow you to track your cat's progress and it will allow us to follow along as well.

He’s currently on 2.5 units of Caninsulin

 

[RosettaSpice]

He’s currently on 2.5 units of Caninsulin

He’s also eating Purina pro plan pate - dietetic management, and Fancy Feast low carb options suggested on these forums. He’s not eating any dry kibble at all, he eats only wet food as it’s easier on his teeth, and seems to be recommended in general.

Open to other suggestions for food, but regardless his number have been very low in a few rare instances, but generally quite high, especially before a shot, sometimes over 20.

 

[CORKY]

Is it in gravy? What’s the flavor??

 

[RosettaSpice]

Is it in gravy? What’s the flavor??

 

[CORKY]

Well according to the calculator and ingredients the dry matter carbs are 1.8% so is great here are the numbers

 

[RosettaSpice]

You can make a unit-to-unit switch from Caninsulin to Lantus. Some members prefer to slightly reduce the dose if starting a new insulin. What is the current dose of insulin you're giving your cat?

It would be helpful for us to see a week or two of your home testing data. This is a link to a post on helping us to help you. It has instructions for setting up a spreadsheet. This will allow you to track your cat's progress and it will allow us to follow along as well.

Sorry I replied to my own comment. He’s on 2.5 units of Caninsulin - any less and his numbers are far too high, pretty well constantly.

I’ve been taking blood samples from his ears, and got a regular human meter. I was told by my vet there isn’t a big difference. But taking many tests results in some bruising..

So if I’m understanding, I should be able to give the same dose of Lantus ? What should I expect or prepare for ? Thanks again for all the replies and help with this.

 

[CORKY]

The bruising may be cause by the lancet being pushed thru the ear, position the lancet forward find a small sock fill tge end with rice to make a small ball that fits on the inside oft he ear tie it, use this to better hold where you are inserting the lancet

 

[CORKY]

 

[Wendy&Neko]

Hello and welcome. I too switched from Caninsulin to Lantus for my cat. Both kitty Neko and I were happier with the Lantus. For one thing, the needle gauge on the U-100 was thinner and easier to give. Plus the insulin just lasts longer in a cat.

We do switch to about the same units, so 2.5 on a U-40 syringe to 2.5 on a U-100 syringe. Lantus is much more concentrated. There are times when we'd suggest a slightly lower Lantus dose to start, based on how low the current Caninsulin dose is taking him. Some cats have a strong reaction to a switch in insulin, so a dose that takes him as low as 100 (5.6) would be a bit high a dose to start. In the link Sienne shared in post #4, is instruction on how to share blood sugar data with us. It means filling in a spreadsheet and sharing it with us. Even the last couple weeks of data are helpful. Without seeing blood sugar data, it's really hard for us to suggest what would be a good starting dose. Also, make sure that when you switch, you can monitor closely for the first day+night or two.