Need more info. Like:
Which insulin are you using?
How much insulin?
Are you testing for ketones?
What meter are you using for testing?
What other BG readings did you get today?
Any changes going on?
Where do you live? so we can make country specific recommendations
How long ago was the diabetes diagnosed?
What food are you feeding, brand style kind?
Age of cat is 14. Name of cat is Nemo
Your name?
Maybe a bit more background. Please.
31.1 * 18 = 559.8 mg/dL high