I would print this document out to share with your vet:
https://www.aaha.org/professional/resources/diabetes_management.aspx. They are the American Animal Hospital Association guidelines for diabetic dogs and cats.
Note in the cat section where is says under "Initiating Insulin Therapy" "Precautions and Details":
- Home monitoring of BG is ideal and strongly encouraged to obtain the most accurate interpretation of glucose relative to clinical signs.34 Most owners are able to learn to do this with a little encouragement, and interpretation of glucose results is much easier for the clinician. See Table 2 for web links to client educational materials.
and
- In-clinic blood glucose curves (BGCs) are more likely to be affected by stress hyperglycemia than BGCs generated at home. Veterinarians should be cautious of high glucose results and subsequent overzealous increases in dose.
I think she may be misunderstanding how stress hyperglycemia works in cats. Bandit has gone up as much as 300 points before from vet stress at the emergency vet, and they tried to convince me that he needed insulin immediately because his numbers were in the 400s. I had just tested him at home a few days prior so I knew he was still in remission, so I told them I wanted to wait a few days and see what numbers he was giving me at home. The Emergency vet scoffed and called my regular vet to tell her that she was seriously concerned for my cat because I was refusing to treat his diabetes! Sure enough, when we got home his numbers dropped back to normal and he did not need to start insulin again. If I had listened to the emergency vet I could have killed my cat with an insulin overdose. Needless to say, we do not see that vet anymore. Bandit's current vet is an internal medicine specialist at Cornell, and he strongly advocates home testing over office testing for all of their feline diabetics.