There is a continous glucouse monitor (CGM) that some people have used for their cats. The Freestyle Libre. No idea of the cost, especially since this is for a cat and Ninja probably doesn't have health insurance that would help cover the cost. Good for 14 days. Have read some comments that it falls off easily. Well, understandable since cat fur grows back fairly quickly and cats will scratch at it and try to remove it.
This article talks about other CGMs available.
You could do a +9 once you go back to work. All data gathering is good. It could provide more information to use with your vet, to show that the duration is not there with the Vetsulin.
Vetsulin isn't an insulin recommended for use in cats, because the duration and control just isn't there. If Ninja was a dog, it would be the appropriate insulin. AAHA Diabetes Guidelines has lots of info.
Here is the section from the guidelines about insulins for cats.
In the UK, Caninsulin (aka Vetsulin) used to be the first insulin that vets could by law prescribe, for dogs or cats. That has changed over the years and the RVC now recommends prozinc for cats as the insulin of first choice. Some vets seem to treat cats as if they are small dogs, which we know doesn't always work.
Some cats do become regulated on Vetsulin. Too soon to say with Ninja.
If you're interested in more reading about insulins for cats vs dogs,
here is a good article. A bit dated, 2015 but still good info.
Here is a second article from 2014 about how Vetsulin is not the first choice for cats.
Best chance of remission is with one of the longer acting insulins and low carb diet. Best chance of remission occurs in the first 6 months.
Managing Feline Diabetes - Current Perspectives is from 2018, published in one of the vet journals.
To me, knowledge is power, so I like to read some of the current thinking on treating diabetic cats and letting people know about some of the resources that are out there. Up to you if you want to read any of these articles.