5/24/26 - New Member (Basil) - Lantus: How long to see any effects?

[Ncstefanie]

Hello everyone! I have Basil, a 5 year old diabetic cat who was in remission for a year and a half (was on Prozinc) but recently relapsed and my new vet put him on Lantus/glargine 1 unit twice daily with a Libre CGM. He has been on it for 10 days but he rarely goes under 300 and many times he's above 400 (reading on the CGM just says HIGH). I’m looking for insight on how long it should take for his numbers to start lowering. Vet and it could take a week or so. But he's lethargic/sleepy and losing weight. Appetite is OK although he's never been a good eater.

I am switching him to wet food now (thanks Dr. Lisa for the great article!!). I’m trying Weruva Cats in the Kitchen Salmon, but he hates the fish chunks so I am going to get another flavor later today. He’s at 75% dry / 25% wet currently eating 3x day. Spreadsheet link in my signature. We did try 2 units but it dropped his numbers very fast down to 80 so vet said to stick to 1 unit. I wish I could do 1.5 units but the pen can’t do that! I am priming it with 2 units before dialing to 1 unit but it almost seems as if nothing is coming out – only a drop or so. Is that normal? I know I can’t use his old U-40 needles, but couldn’t I get U-100 needles to administer half doses? Vet said you can’t use needles w/the pen (?). I am so worried about him. Thanks for all advice & insights. This board is amazing, I wish I had found it the first time he was diagnosed.

Also, question regarding the CGM: The app says “Sensor ends in 4 days” but if it is still well attached, can it stay on longer?

 

[CORKY]

@Staci & Ivy

 

[Staci & Ivy]

Hello everyone! I have Basil, a 5 year old diabetic cat who was in remission for a year and a half (was on Prozinc) but recently relapsed and my new vet put him on Lantus/glargine 1 unit twice daily with a Libre CGM. He has been on it for 10 days but he rarely goes under 300 and many times he's above 400 (reading on the CGM just says HIGH). I’m looking for insight on how long it should take for his numbers to start lowering. Vet and it could take a week or so. But he's lethargic/sleepy and losing weight. Appetite is OK although he's never been a good eater.

I am switching him to wet food now (thanks Dr. Lisa for the great article!!). I’m trying Weruva Cats in the Kitchen Salmon, but he hates the fish chunks so I am going to get another flavor later today. He’s at 75% dry / 25% wet currently eating 3x day. Spreadsheet link in my signature. We did try 2 units but it dropped his numbers very fast down to 80 so vet said to stick to 1 unit. I wish I could do 1.5 units but the pen can’t do that! I am priming it with 2 units before dialing to 1 unit but it almost seems as if nothing is coming out – only a drop or so. Is that normal? I know I can’t use his old U-40 needles, but couldn’t I get U-100 needles to administer half doses? Vet said you can’t use needles w/the pen (?). I am so worried about him. Thanks for all advice & insights. This board is amazing, I wish I had found it the first time he was diagnosed.

Also, question regarding the CGM: The app says “Sensor ends in 4 days” but if it is still well attached, can it stay on longer?

Hi Stefanie and Basil, welcome!
If you are switching Basil to low carb wet food, he may react to that and begin to drop his glucose levels quickly.
So caution must be used to give increases as you are switching his food.
Some cats react to diet changes to low carb wet alone and their glucose comes down fast.

You are correct that you absolutely can use U100 syringes with Lantus and can use them with the pens (you use it just like a vial, and never shoot insulin back into the pen, it will contaminate the insulin).

If you have a Walmart near you, their Relion brand is very inexpensive (around $12) and they do carry 1/2 unit syringes. I’ll add a picture here, this box is for the shorter 6 mm needle length. Some manufacturers carry a little bit longer 8 mm needle.

As for the Libre, I will also attach a link that we have created with lots of information about using a Libre.
Getting Started With Continuous Glucose Monitors (CGMs) for Diabetic Cats

I also highly recommend joining the Facebook Group Freestyle Libre for Dogs and Cats. There’s an extensive amount of valuable information on that page.

The Libre will only work up to 14 days for a Libre 3 and up to 15 days for a Libre 3+.

Even if it is still well attached, it will shut down automatically at exactly the designed amount of days.
If you would like to continue using one, you will have to install a new one.
If you follow the instructions carefully, it’s really pretty easy to install them, I keep one of my cat 24/7 for the past three years.

It’s also very important to know how to ear prick your cat and blood test with a handheld glucometer, especially in the instances where they can go LO on the Libre.
Many times they can actually be higher (on a handheld device) than the Libre reads when in low ranges.
You are correct that the Libre only says HI when the glucose values are 400 and above.

I hope this helps and you will start to see lower BG.
Keep asking questions and post daily to get guidance and help

 

[Sienne and Gabby (GA)]

Welcome to FDMB.

I'm guessing that you've looked over the dosing methods for Lantus since you mentioned using SLGS on your spreadsheet. Keep in mind that you want to evaluate the dose after 7 days. Given what Basil's numbers look like, it seems like it's time for a dose increase. We typically increase doses by 0.25u but you will need syringes to do that. You actually could increase by more but with a change to a lower carb diet, I'd err on the side of being conservative.

If you've not had a chance to look over the sticky notes about Lantus, they are at the top of the Lantus board.

If you're switching over to a syringe, which is what we recommend, you do not need the needle tips for the pens. There is a rubber stopper at the top of the pen. You insert the syringe into the rubber stopper (hold the pen with the stopper pointing to the floor) just like you would have done with a Prozinc vial.

 

[Ncstefanie]

Hi Stefanie and Basil, welcome!
If you are switching Basil to low carb wet food, he may react to that and begin to drop his glucose levels quickly.
So caution must be used to give increases as you are switching his food.
Some cats react to diet changes to low carb wet alone and their glucose comes down fast.

You are correct that you absolutely can use U100 syringes with Lantus and can use them with the pens (you use it just like a vial, and never shoot insulin back into the pen, it will contaminate the insulin).

If you have a Walmart near you, their Relion brand is very inexpensive (around $12) and they do carry 1/2 unit syringes. I’ll add a picture here, this box is for the shorter 6 mm needle length. Some manufacturers carry a little bit longer 8 mm needle.
View attachment 78372
As for the Libre, I will also attach a link that we have created with lots of information about using a Libre.
Getting Started With Continuous Glucose Monitors (CGMs) for Diabetic Cats

I also highly recommend joining the Facebook Group Freestyle Libre for Dogs and Cats. There’s an extensive amount of valuable information on that page.

The Libre will only work up to 14 days for a Libre 3 and up to 15 days for a Libre 3+.

Even if it is still well attached, it will shut down automatically at exactly the designed amount of days.
If you would like to continue using one, you will have to install a new one.
If you follow the instructions carefully, it’s really pretty easy to install them, I keep one of my cat 24/7 for the past three years.

It’s also very important to know how to ear prick your cat and blood test with a handheld glucometer, especially in the instances where they can go LO on the Libre.
Many times they can actually be higher (on a handheld device) than the Libre reads when in low ranges.
You are correct that the Libre only says HI when the glucose values are 400 and above.

I hope this helps and you will start to see lower BG.
Keep asking questions and post daily to get guidance and help

Hi Staci - I will definitely ask the vet about the U100 needles when I speak to her on Tuesday. I was hoping the CGM would continue to give data as long as it was attached, but I guess that’s too much to hope for. :/
I will check out that Facebook group too thank you!

 

[Ncstefanie]

Welcome to FDMB.

I'm guessing that you've looked over the dosing methods for Lantus since you mentioned using SLGS on your spreadsheet. Keep in mind that you want to evaluate the dose after 7 days. Given what Basil's numbers look like, it seems like it's time for a dose increase. We typically increase doses by 0.25u but you will need syringes to do that. You actually could increase by more but with a change to a lower carb diet, I'd err on the side of being conservative.

If you've not had a chance to look over the sticky notes about Lantus, they are at the top of the Lantus board.

If you're switching over to a syringe, which is what we recommend, you do not need the needle tips for the pens. There is a rubber stopper at the top of the pen. You insert the syringe into the rubber stopper (hold the pen with the stopper pointing to the floor) just like you would have done with a Prozinc vial.

Thank you, Sienne . I definitely want to switch to the syringes because I can’t tell what he’s actually getting with the pen. Plus one of the five pens wouldn’t prime at all. It just irked me because I was having a text conversation with the vet on Friday and I asked her if there were any other needles I could use with the pen and she said no. That didn’t seem logical to me. I’ll also investigate the Lantus message board further. I’m amazed at how many great resources are here! You all have done such a wonderful job.

 

[Christie & Maverick]

Hello and welcome! Basil sure is a cutie. I agree with using the insulin syringes rather than dosing just by pen, since they will help you to draw up the smaller dose increments. One point of clarification though, the insulin pens work off negative pressure, so you don’t treat them exactly like a vial, meaning that you want the insulin syringe to be to zero line, insert into the rubber stopper, then draw out the insulin. You don’t want to put air in there. With the vials, the technique isn’t the same, since you would be drawing up air into the syringe first, then injecting the air into the vial, then drawing out the insulin.

Here is a pic of a pen,

and one of just the cartridge, which is what I used to use. Basically the same, just without the extra pen outer packaging.

 

[squeem3]

You can buy U100 syringes from Amazon with no prescription. Other web sites may ask for a prescription or the phone number of the vet, depending on what your state law is.

You want U100 3/10cc with half unit markings.

The Relion syringes have half unit markings even though it's not specified on the box. You'll need a prescription to buy insulin syringes from a store pharmacy.

 

[Ncstefanie]

Hello and welcome! Basil sure is a cutie. I agree with using the insulin syringes rather than dosing just by pen, since they will help you to draw up the smaller dose increments. One point of clarification though, the insulin pens work off negative pressure, so you don’t treat them exactly like a vial, meaning that you want the insulin syringe to be to zero line, insert into the rubber stopper, then draw out the insulin. You don’t want to put air in there. With the vials, the technique isn’t the same, since you would be drawing up air into the syringe first, then injecting the air into the vial, then drawing out the insulin.

Here is a pic of a pen,

and one of just the cartridge, which is what I used to use. Basically the same, just without the extra pen outer packaging.

Christie- WOW I NEVER knew that about the syringes. When they originally showed us it was a straight draw from the vial like you are describing with the syringe and the pen! yikes!

 

[Ncstefanie]

You can buy U100 syringes from Amazon with no prescription. Other web sites may ask for a prescription or the phone number of the vet, depending on what your state law is.

You want U100 3/10cc with half unit markings.

The Relion syringes have half unit markings even though it's not specified on the box. You'll need a prescription to buy insulin syringes from a store pharmacy.

Thanks Squeem - I'll be talking to my vet on Tuesday - good info!!

 

[squeem3]

Some brands:

You don't need the veterinary specific ones. There's no difference between them and Human syringes other than costing twice as much.

If you buy from a pharmacy double check the box of syringes before you pay. Sometimes pharmacists give you 1/2cc or 1/2 inch long needles and insist that it is what you want. You don't. You want 3/10cc with half unit markings. Needle length and gauge is preference but many people like 5/16 inch 30 or 31 gauge.

 

[soreto]

it's totally normal for it to take a while for kitty to get out of the high BG #s with glargine. i'm attaching my kitty's Chart from when he was first diagnosed last year. you can see how high the #s are. he is doing well now & in normal BG 99% of the time. (also, his dosage has been lowered to 0.5u nowadays)

as for food, try the weruva BFF OMG Gravy!. it's for cats that like to lick the gravy. most of the flavors are under 10% carb.