Cat has diabetes and now has hyperthyroidism

by Susan Calder
(Ottawa, Canada)

Dear Dr. Neely;

I wrote you about a week ago, about my cat Chirpie. She was diagnosed with diabetes in December. She has been on 4 units of Caninsulin insulin for now 7 weeks.

I took her to my vet on Thursday, January 15, to have follow-up bloodwork. I got the results yesterday, and was informed she had hyperthyroidism. She is now taking the insulin, and 1/4 tablet of Tapazole. I was also told that her being on the insulin had not changed any of the bloodwork from the previous bloodwork 7 weeks ago, except for now having hyperthyroidism.

My vet is now doing bloodwork on her pancreas and a urine culture. Her white blood cell count came up from the last results, which I was told was good. She continues to sit by the water/food bowls and crouches continuously. I know cats are very good at hiding things, and the crouching means she is uncomfortable or in pain. I have this fear she has cancer, because the insulin is not working.

Do you believe she is on the right insulin, or could she have an infection without having a temperature? Her lungs are clear, but if you touch her nose she sneezes, and she never did that before. I truly appreciate your advice.

Thank you so much, and God Bless.


Dear Susan,


I am sorry to hear that things are so complicated with Chirpie. I would very much like to help, and in order to do so, there is a lot of information I would need.

First, I would like to say that it is strange that 7 weeks ago Chirpie didn’t have hyperthyroidism and now she does. The only likely explanation I can see for this is that perhaps your veterinarian didn’t run a thyroid test in the initial bloodwork. Is that the case?

In regards to her insulin: Is it being given twice daily? If it is not, this could be the cause of the lack of change in her glucose levels. Insulin needs to be given at roughly 12-hour intervals to manage blood glucose. In general, Caninsulin is a good choice for cats because it is pork-based. However, cats can react differently to different types of insulin, so it is certainly possible that she needs a different type.

I’m unsure as to whether or not this has been done, but glucose levels should be checked 10 days after an initial insulin regimen is put in place or a dosage change has occurred. 7 weeks should never go by without a follow-up glucose level. Insulin will reach its peak effectiveness at the present dose in 10 days, and adjustments should be made at that time.

Without knowing her exact glucose levels, I would like to mention that some cats have an elevated glucose level simply from going to the vet or in reaction to stress of any kind.

Diabetes and hyperthyroidism share many of the same symptoms. Crouching near her water bowl is consistent with both diabetes and hyperthyroidism. It does not necessarily indicate that Chirpie is in pain. Her presence at the water bowl may also be the reason for her sneezing. If she is drinking more or drinking constantly, her nose could be wet often. It is also possible that she is, in fact, fighting an infection, or as I had said previously, she may have an issue with her teeth or some other underlying issue.

If you wouldn’t mind sharing her results, I would be very interested in knowing the levels of her bloodwork, especially her glucose and thyroid values. In fact, reviewing the results of all of her bloodwork would be very useful. Additionally, glucose readings from various points throughout the last 7 weeks would also be useful if she has had follow-up tests during that time.

To help put your mind at ease, from what you described, it seems that cancer is unlikely. I would like to help more, but as you can see, this situation is quite complicated. If you could email us or submit a question again containing your telephone number so we could try to arrange a time to speak about this case directly, I could much more easily give you a second opinion. If you submit a new question containing your phone number, please rest assured that it will NOT be posted publicly on the website. All submissions are emailed privately to us for approval and reviewed prior to being posted on the site.

Looking forward to hearing back from you,
Dr. Neely

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