I am sorry to hear you are worried about your cat.
I am a veterinarian and will do my best to help.
I don't like to use Lexicon long term in cats. It has been associated with causing kidney failure in some cats.
If it is allergies, I would try the antihistamine cyproheptadine (Periactin).
If a chest Xray has not been done, I would do that. If he has asthma, he needs to get steroids. You could use inhaled steroids; that would not be absorbed much systemically and should not interfere with the diabetes.
I hope you can see what I am writing in live chat; I am not seeing responses from you.
A chest Xray would tell us if he has asthma, or an enlarged heart.
I will try another format to contact you, if I do not hear from you. Maybe this live chat is not working for us.
Thanks Rebecca, I will pass on your suggestions. We are becoming increasingly concerned about our cat. Our vet seems rather reticent in giving him anything steroid based. He has not had an x ray.
I have treated diabetic asthmatic cats with the inhaled steroids. When given with an inhaler, the steroids are just in the lungs, and should not cause systemic side effects.
But first get a chest Xray and see if asthma is what he has.
You can try children's nose drops once daily, if his nose seems stuffed.
And the Cyproheptadine may help.
Is there anything else I can answer or help with?
Thank you-this gives me hope.