Possibly diabetes..

[DreamingOfSummerDays]

So Dcat is currently at the vet. First lot of bloods have said -
Liver enzyme issue
High white count
Possibly diabetes

Currently on antibiotics to treat any possible infection.

If your cat had diabetes, how is this treated? What's the rough monthly cost?

Our old cat had diabetes. Hers was due to having a damaged pancreas and was treated with twice daily insulin injections.
It is generally easy to do but I will admit it is quite tying as you need to be home to do the injections. We were lucky as our vets has a cattery st the back so she stayed there when we went away. Our cat was a tricky case as she also had IBD so her insulin requirements varied but our neighbour had an easy cat.
Your vet can give you a prescription to buy the insulin online which is cheaper than directly from the vets. Again the syringes I bought online-you need to be careful you buy the right ones.
I also bought a glucometer (£20ish from local chemist) so we could do readings and glucose curves at home.
The vet and/or vet nurse will go through everything with you. Ours were fantastic and very helpful so I hope yours are. However, fingers crossed yours isn't diabetic.

As @Vinorosso74 said, but I would adv. the alpha track home monitor that is calibrated for dogs and cats as the human monitor can be up to 10% inaccurate for monitoring dogs and cats.
Cats can also give up being diabetic and switch diabetes on and off so they are much, much trickier than dogs or humans.

Our vet loaned us an alphatrack monitor for some late night/early morning readings. It was clearly a superior bit of kit to what I bought! We did take the one we bought to the vets to compare readings and luckily they were almost identical.
An updates on your cat OP?