Welcome to you both.
Apologies in advance for bombarding you a bit with info/suggestions but it's the holiday season and I want to get the info to you fast enough for you to act on it.
Not eating is a problem for an otherwise healthy cat and an even bigger problem for a diabetic cat who needs insulin.
Re the eating difficulties, is your kitty showing any signs of nausea? Could your kitty be constipated? Here's a helpful article to help you identify clinical signs and also appropriate treatments:
Nausea, Vomiting & Appetite Problems - Symptoms and Treatments (from Tanya's Site)
Because of how their metabolisms work it is vital that a cat eats regularly. For a diabetic cat receiving insulin regular food intake is even more important, firstly to ensure that you can give insulin safely but also to ensure that the cat doesn't start producing ketones.
I'd strongly recommend:
1. Calling your vet today (Saturday). If possible try to get in today for a check-up (esp if an exam for possible constipation issues is needed). At minimum ask for input on dosing/token dosing and, if nausea and/or inappetence are still present ask for suitable prescriptions - BOTH anti-nausea AND appetite stimulant medications - you can administer at home over the next few days (Christmas, and all that). (Note: if constipation's the cause of the nausea a short course of Reglan (metoclopramide) can help improve normal gut motility - need vet check to make sure there're no blockages.)
2. Pick up a glucometer (e.g. Walmart Relion Micro or Confirm), a good supply of test strips for your meter type, and 28 gauge lancets for home testing (we can teach you how).
3. Check out the
Hypo Tool Box for a list of other supplies to pick up on your shopping trip.
4.
VERY IMPORTANT - pick up some
ketone test strips (Walmart have some in their Relion range. Ketostix or Keto-diastix are other commonly-used strips.) Test your kitty's urine
daily for ketones for the time being so that you'll be in a position to act straight away if ketones start forming. (See below.)
If a diabetic cat doesn't get enough food and insulin the body will start breaking down fat stores to use for energy. As a result ketones may start building up in the blood and this can lead to diabetic ketoacidosis, a condition that requires emergency veterinary treatment in a hospital setting. Ketones can build up quite quickly. Monitoring your kitty's urine for ketones will put you in a position to act to
prevent DKA. For information: if a trace positive ketone result is obtained call vet straight away for advice; if any higher than trace kitty needs to be taken to a vet immediately for emergency treatment to reduce ketone levels and avoid DKA. Some helpful links:
Are you testing for ketones?
Urine testing tips
(NB!!! I'm not trying to scare you here, just making sure you are aware of DKA risks because your kitty requires insulin and she isn't eating enough at the moment. I'm just trying to put you in the position where you can monitor your kitty for ketones so that you'll be able to act straight away to help her should the need arise. (Unfortunately many vets don't seem to give any form of briefing on ketosis and DKA in their introductory training for caregivers of FD cats.)
Here are some other helpful links:
Persuading your cat to eat
How to Treat Hypos - (Read this through. Print out a copy and keep it where you can lay hands on it quickly should you need it.)
Again, sorry for the 'baptism of fire'

but I'm erring on the side of caution: kitties seem to have this uncanny knack for throwing wobblers when the vet is closed.
Hope she eats for you this evening.
Mogs
.