Why Is It So Hard To Regulate My Diabetic Cat? – Ask Dr. Joi

By Dr . Joi Sutton|2017-02-20T11:25:35-05:00Updated: February 16th, 2017|Pet Care, Pet Diabetes, Pet Newsletter|10 Comments
  • Older Cat Yawning

I get some great questions from clients. They inspire me with article ideas and keep me in tune with diabetic pet owners. I enjoy interacting with our readers, and sometimes the questions are worthy of a newsletter. I bet if one person has this question and takes the time to write me, there are likely lots of folks with a similar question. Let’s jump right in and talk about this one about insulin resistance and regulating a diabetic kitty:

I have a diabetic rescue cat who was diagnosed a little over two years ago. So far, I have been unable to regulate his sugar levels. I’ve tried everything including switching him from ProZinc to Vetsulin. He is on a canned food diet as well. He is currently getting 12 units twice a day and I still can’t get his BG under 250. He has been vetted and we can’t find any underlying conditions that would explain his insulin resistance. Pushkin is 12 years old, neutered and indoor only. Beyond his diabetes, he seems healthy and content, however, he is always hungry and thirsty and always peeing. My vet and I are at a loss. Is there anything left to do?

Answer: 12 units is a pretty high dose for a cat. When I hear of such a high dose I think of a couple situations. The best case scenario would be a Somogyi swing. That happens if we have a pet at too high of an insulin dose for that pet’s needs, and the blood glucose plummets. If the dose is too high and the pet becomes hypoglycemic, the liver reacts to a low blood glucose by making more sugar. It can be really hard to catch this situation! When I suspect Somogyi I’ll drop the dose and do a curve a week later.

Honestly, when we start treating diabetes we don’t know if the pet will require just a smidge of insulin or a bigger dose. The pancreas may yet be making some insulin. Absorption and metabolism of insulin also varies from pet to pet. We don’t know what the correct insulin dose will be for any particular pet! It’s an important point, so I’ll repeat myself: Insulin absorption and metabolism varies between pets. Blood glucose curves don’t always result in us raising the dose. Sometimes we lower the dosage.

When you started him in insulin did you start at a low dose and slowly sneak up in the dose? Do you remember how quickly you bumped up his dosage way back when he was first diagnosed? I think folks can be so excited to fix the situation quickly that they raise the dosage too fast. Slowly and surely sneak up on the dosage. Curves tell us how long insulin lasts in a pet and how low the blood glucose goes for a particular pet with a particular insulin at a particular dosage. If I alter the insulin dosage I will wait 5 to 7 days until I do another curve.

The other conditions I’d consider are Acromegaly and Cushings disease – both can cause awful insulin resistance. Both of these diseases are rare but do exist in cats. I’ve never seen an Acromegaly cat. I have diagnosed a cat with Cushings disease. Both these diseases make managing diabetes very, very difficult. I advise an internist consult if your vet suspects Cushings or Acromegaly. Cushings is one of my least favorite diseases of all-time and I usually punt them to my local internist. Frankly, if your vet has expressed frustration in regulating your cat, seeing an internist is a great idea. Becoming a vet takes 8 years of college. Internists get yet another 4 years of training to put those extra letters behind their names.

Pzi/Prozinc is usually a better choice for a cat than Vetsulin, although there are cats that do well on Vetsulin. Vetsulin just doesn’t last very long in most cats. There are some cats that are regulated with Vetsulin, but by the tail-end of the 12 hour dosage, the glucose is usually high. Other good choices for cats would be Levemir or Glargine. They cans be purchased in 3cc pens to save on costs.

You are smart to look for underlying causes of disease and insulin resistance. Big ones include dental disease and urinary tract infections.

I’m so glad you are using canned only food! Which is it? Have you checked the carb content? The lower the better. My personal favorite for cats is Purina DM canned which has 4 percent carbs. Of course cats get a vote in what they decide to eat, and you can find the carb content of most cat foods on the Internet with a Google search.

Have you and your vet ever dropped the dose down to a low starting dose throughout this? As veterinarians we don’t often use urine glucose testing anymore once the home glucose meters became so prevalent and easy to use. Nonetheless, one way to diagnose Somogyi swing is checking the urine for glucose. If it is high in the morning and then you find no or little glucose in the urine a few hours later, it might make us suspect this situation.

Chat with your vet and keep me posted!

Have a question or comment? Post below or email me at [email protected]. I always enjoy hearing from my readers!

NOTE: Consult your veterinarian first to make sure my recommendations fit your pets special health needs.

About the Author: Dr . Joi Sutton

Dr. Joi Sutton is a 1993 graduate from Oregon State University. She has practiced both in emergency medicine and general practice. Dr. Sutton has done extensive international volunteer work though Veterinary Ventures, a nonprofit organization that takes teams of veterinarians to undeveloped countries for humane medical care. She also runs a small animal practice in South Florida. Connect with Dr. Joi on LinkedIn


  1. Cherry Sewell March 28, 2021 at 8:24 pm - Reply

    Hi Dr Joi! My cat was diagnosed with diabetes just over 2 months ago. My vet put him on Caninsulin (Vetsulin) using the pen as it is apparently the only insulin approved for veterinary use here in Australia. In any case – he was on 3 units morning and night and he quickly responded well by putting on weight, drinking normally and urinating normally again. His hunger also abated. But after a week or two, I noticed he was like a zombie for most of the day and my vet told me to drop his insulin down to 2 units 2x per day, which is the dosage he is on now.

    Also, within a week of diagnosis, I changed his food completely – took away the kibble and fed him raw (commercially produced and balanced food) as well as some ZiwiPeak (air-dried raw food) and some lean steak cubes as his treats. I am keen to get him into remission, so, as my vet does not agree with me home testing with a BG monitor (as it is apparently painful for the cat and would ruin our relationship she says) I am now monitoring his urine using Diastix.

    My question is – is it normal to have 0 glucose in his blood all the time? I test mornings (but unfortunately it is always just after his morning shot as he runs outside to pee after eating and insulin) and midday. I haven’t managed it in the evening because it’s harder to catch him at that time. What does this mean? My vet only wants to do a fructosamine test in 3 months which will be 5 months after his diagnosis – and only one month before the 6 months marker, after which I have read it is unlikely he will go into remission. But with 0 BG showing up in his urine consistently – does this point to not needing insulin, or getting too much still – even though no really obvious signs of the zombie cat I saw before?

    • Dr . Joi Sutton April 4, 2021 at 9:30 pm - Reply

      I absolutely think you should check your pet’s blood glucose at home. I can imagine not testing blood glucose at home if my cat was diabetic. I have an article on this website called Tips and tricks for collecting the perfect blood sample from your pet. Urine glucose testing is crude as the threshold in the kidneys for glucose spilling over into the pee is somewhere around 250 to 300 mg/dL for cats and somewhere around 200 for dogs. So of course it can come up zero on a urine dipstick. You might also google the 2018 AAHA Diabetes Guidelines which is packed with information on pet diabetes.

  2. Amina & Mrow September 29, 2019 at 11:05 pm - Reply

    Hi everyone; M’row about 16 years old, neutered, never fat/chubby/obese was diagnosed with diabetes nine months ago. He’s doing great; started 1U lantus twice a day, after 3 months I dropped this down to 1/2 unit twice a day. I never knew about the dangers of kibble until his diagnosis, but he went right on fancy feast pate immediately. We were lucky, as he prefers this to kibble. He’s going to the vet soon, as now he’s down to 1/2 U lantus once a day
    Anyway,I’m actually writing about feeding frequency; in the wild, cats eat (nibble?) frequently throughout the day, as they catch something, eat it, catch the next thing, eat that, and so forth. So M’row has food available all the time I’m awake. I put down another can (3.5 ounces) when his bowl is cleaned up. Occasionally he’s hungry in the morning when I’m still asleep; then he nibbles gently at my toes. Every cat is different, of course, but I think this open feeding is more physiologically normal. Mayhap I would change it up if he were obese, yes I would. For treats he gets dried meats; gotta watch those carbs!

    • Dr . Joi Sutton October 19, 2019 at 10:18 pm - Reply

      Nibbling throughout the day may be what a cat prefers, but if a cat is diabetic, it is best to receive the majority of calories when the insulin is given. Make sense?

  3. lu bc February 17, 2017 at 6:19 am - Reply

    My cat had dental work that needed to be done, which was causing high BG due to the infection. Once taken care of, insulin needs dropped sharply — something to be careful about (once done) so as not to overdose your cat with insulin afterward.

    I understand Somogyi is still just a contested hypothesis needing proof.

    • Dr Joi February 18, 2017 at 7:00 am - Reply

      Great point about dental infection!
      I’ve seen somogyi occur. I don’t at all consider it unproven.
      🙂 Joi

  4. Wil February 16, 2017 at 10:08 pm - Reply

    Very good article. I have my cat on Fancy Feast pate. This is a good website for canned food information. http://catinfo.org/commercial-cat-foods/#Commercial_Foods

    • Dr Joi February 18, 2017 at 7:01 am - Reply

      Yes, that Website has a fantastic cat food composition chart. Thanks for bringing it up. 🙂 Joi

  5. Wendy Hardcastle February 16, 2017 at 2:02 pm - Reply

    Dr. Joi, just a little input from an individual with 2 diabetic cats. I have had diabetic cats in the past also and also dealt with 2 other cats with cancer giving chemo RX. Regarding the person having a hard time regulating her cat and was giving 12 units 2X per day, that is a scary situation to me. Luka (his dosage was set, after a few curve tests at 4 units in the a.m. and 3 units in the p.m.) has been on vetsulin for almost 2 yrs now and is holding his own very well. One thing not addressed is her feeding schedule – I think this is one thing that has been of great help to Luka (and Star who was diagnosed almost a year ago). I adhere to a 12 hr. schedule as close as I can, of course there are times that being off just can’t be helped, but the next day I adjust the time frame and by the next day we are back on schedule. I also feed high protein foods. I know that you are very aware of the above info and enjoy reading about these questions and comments. Thanks

    • Dr Joi February 18, 2017 at 7:03 am - Reply

      I totally agree. Sticking to a 12 hour feeding schedule is ideal. It’s best to take in the majority of calories when the insulin is given. With low carb diets there is not as much of a glucose spike if a little snack it taken between meals, but if we can convince cats to eat equal meals every 12 hours we get improved blood glucose control for sure! Thanks for the post! 🙂 Joi

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