Need some guidance

[Chaseypoo1819]

Hi everyone, my cat Chase is 14 years old and was diagnosed with diabetes in April 2025. His blood work showed him at 570 mg/dl.

The vet started him on a timed feeding diet, Hill’s m/d GlucoSupport dry food (1/4 cup) and Hill’s m/d GlucoSupport wet food (1/2 can) in the morning and at night. We started him on Vetsulin 1 unit BID. His glucose curve (5/2/25) showed him getting to a low of 400 and rising again just 4 hours after injections. We upped it to 2 units BID and his curve (5/23/25) showed a low of 327 and rising after 4 hours. Then 3 units BID, curve (6/20/25) showed a low of 318 and rising after 5 hours. 4 units BID, 7/3/25 curve showed a low of 278 and rising after 4 hours. And then 5 units BID curve on 7/25/25 showed a high of 77 1 hour after injection and a low of 44 7 hours later.

The vet warned me that he might be going into remission and to watch out for a hypoglycemic episode. Then he went hypo the next night and was stumbling around, walking into walls, not responsive to his name or my voice like normal… gave him karo syrup and took him to the vet ER.

I started checking his BG at home (idk how accurate it was) but was told to skip dosages if he was under 200. We had moved to 2 units BID.

His 8/15/25 fructosamine was at 463 and his second fructosamine was at 725 on 9/14/25. At this point we had no clue what was going on with him so we started with a FreeStyle Libre around 9/26/25 and he was on 4 units in the AM and 3 units in the PM. There were still days where he was hitting 60-80 at night but would have a sharp curve up. The vet said that vetsulin was no longer working for Chase and that we needed to change insulin types on 10/24/25.

Started Prozinc 1 unit BID on 10/29/25. He was on that dosage for about 1.5 weeks before we put on another Libre. Started 2 units BID on 11/8/25. 11/10/25 started 3 units in the AM and then 2 units PM. Then changed to 3 units BID on 11/13/25.

He was having smoother curves on Prozinc but started getting some weird curves recently with late nadirs. Today I injected at 7:13am and he dipped under 400 around 9:30am but stayed in the 350-390 range until 4pm. Then he randomly started dropping? He got to 167 at 6pm just from that morning dose. He hasn’t even curved this late from a morning dose. I debated injecting him again but then he started spiking back up and was at 400 by 8:15. I did give him 2 units instead of 3 at 6:42pm but that hasn’t started doing anything yet.

Current dosing schedule is 3 units around 7:15am and 3 units around 6:15pm.

Questions:

• is 3 units BID of Prozinc a lot?
• Why is he starting to curve so late?
• I thought the point of us switching to Prozinc would be so he’s not dropping and gaining as sharp
• My vet told me I shouldn’t use fancy feast pate even though the carb content is so much lower than Hills because it’s a fast release and more prone to sharp curves than hills. I’ve just seen so many success stories with fancy feast. And he’s having sharp curves regardless
• Injection site rotation and how much it affects absorption? She told us to take the fatty part of his neck/ upper back and poke deep into the fatty area.

 

[Wendy&Neko]

Hello and welcome. Looks like you've had a bumpy start. Vetsulin (called Caninsulin elsewhere) is a great insulin for dogs, but doesn't last long in cats. Good thing you switched. Prozinc, along with Lantus are the two recommended insulins for cats. We'll just have to see if it's possible to dial him into a better dose. We tend to change doses by 0.25 units at a time, cats respond to smaller dose changes. 3 units isn't what I would call a lot of insulin. Especially given the higher carb diet he's on.

The m/d is not a good food for diabetics. It's too high in carbs, plus it's expensive. The best food for cats is low carb wet or raw food. Fancy Feast pate are fine, as long as your kitty does not have kidney disease. It's a bit high in phosphorus for a kidney kitty. There are a lot of other good low carb options besides FF, available at most pet stores.

We'll be able to better help you with dosing and questions about his numbers if you could put together a spreadsheet with his values. Just the last couple of weeks is enough to start. Details on how to do that in here: New? How You Can Help Us Help You!

This post has some videos and tips on shooting: How to "Shoot" Your Cat. You don't need to shoot deep, you want to be under the skin, not into muscle.

 

[Sienne and Gabby (GA)]

Whether a dose of insulin is a large dose depends on how you got to the dose. If you started out on 3.0u, that would be a lot. If you worked your way up from 0.5u, for example, in small increments, 3.0u may be the dose your cat needs. We let the blood glucose numbers provide the data to make decisions about dosing. Wendy's point about the influence of a high carb food on dose is also very relevant.

When a cat has a nadir can vary. My cat had an early nadir except for those times when she didn't. The "shape" of the curve can and does vary. (Cats hate to be predictable!)

I disagree with your vet's perspective on food. Many cat's do well on Fancy Feast. They also do well on other brands (e.g., Tiki Cat, Weruva) that are low carb. They are also much more expensive. I'd also encourage you to take a look at the ingredients in what you're vet is recommending. My favorite ingredient in the WD dry food is powdered cellulose (aka sawdust). I would suggest feeding your cat the best quality, low carb food you can afford and that your cat will eat. Also, consider that human diabetics are not eating a prescription diet. They eat a low carb diet. It's the same for cats. A raw diet is also acceptable.

I gave injections to my cat in her scruff. I didn't deliberately rotate the spot and I gave shots in the general area for 6.5 years. It was fine.