I don't understand what it is you're waiting to see or hear. So far 14 different members have all urged you to do the same thing, whatever insulin you choose you need to get on this right now. What I don't understand is you thinking there are no symptoms. The number you just posted, 374 is the symptom.
I got The Lantus. It is the brand name for glargine. There is a Lantus savings card on the Lantus site and will cost 99 dollars plus tax. Your Trupanion will cover most of it. I believe you only pay 10% depending on what plan you have . So 10 dollars and it lasts you 6 months. Pet insurance also covers the pet meter Alphatrack the Libre sensor and everything diabetes related. For the Libre sensor you can use the Good RX discount. Walmart has 2 for 70. After insurance you pay 8 dollars for 2. You need to start insulin asap. the more you wait the more you are hurting the kitty,s chances at remission. You know what they say smart people learn from others’ mistakes.
Don't forget the $5,000-$9,000 price tag for the "aggressive management" and hope it doesn't happen 3 times in a month... Ask me how I know
It's not just about the BG number. Some cats have high numbers and don't produce ketones (until they do) which is the cause diabetic ketoacidosis (DKA). I wasn't fortunate enough to know he was diabetic before he developed DKA, but his BG number when we took him to the first ER was 334. We very quickly became concerned when he started acting lethargic and stopped eating (he never refuses a meal). By the time I was actually able to get him into an ER about 12 hours later (because they were all at capacity and not accepting patients when he became sick) he could barely hold his head up. When they discovered he was in DKA they told me DKA only has about a 60% survival rate (with aggressive treatment/hospitalization -- without it the survival rate is 0%) they said they weren't sure he'd make it through the night and asked if I wanted to euthanize him instead of taking a chance on spending all that money with the very real possibility he may not make it. I opted to try after agreeing to the $8000 estimate. He thankfully did make it and I started giving him insulin and testing him frequently. The second time it happened (21 days later) his numbers were in the high 200s/low 300s. The third time it happened it was less than 24 hours in the 400s. I'm terrified it's going to happen again, so I now test him 15-20 times per day and have to give him sub-cutaneous fluid injections everyday. We're still not sure he's going to be able to make it in the long-term. He went from being 9.5lbs to 5.9lbs. He's lost over a pound since this all started a little over a month ago (that's a lot for a cat) and that's with eating about 3 times the amount of food a normal cat should have. DKA is the worst complication that can happen to a diabetic cat, but certainly isn't the only thing. Dehydration, vomiting, severe depression, problems with motor function, diabetic neuropathy, cateracts and renal failure are among the possible outcomes from untreated feline diabetes. Many of these complications may not be observable (ie. depression, dehydration, etc).
We have a saying here, start low and go slow. You won't be pumping a liter of insulin into her; you start at a low dose, test, do a few curves and see what works.
I don't know where you were given that information the ONLY time you might be advised to withhold insulin is when you're just starting out and if you see a preshot of 200 on SLGS or 150 on TR even then it's unlikely you'd completely withhold. Remission is when you see mostly double digit numbers with only a few in the lower 100's and you've successfully worked your way down the dosing ladder. I doubt she's dropped at all 384, 374, 364 these are all basically the same, there are so many variables that can fudge the numbers 10 mg/dl even just waiting another 30 min to feed or meter inaccuracy's try to remember the higher the numbers go the less precise the meters become. I wouldn't worry too much about withholding once you start after a month and who knows how much longer your probably gonna have a hard time drawing her numbers down... A fructosamine has kind of become irrelevant. You now have about 3 weeks of separate test all saying the same thing all the frutosamine is gonna do is average out those three weeks and spit out a higher number than you've seen so far (because I'm guessing your testing several hours after food so she could be spiking into the 4 or 5 hundreds post meal). To be blunt this is about as bad as withholding food, with what we've seen she is without a shadow of doubt diabetic and there are only 3 humane option's you have, treat her with insulin (preferential), you give her to someone who will treat her with insulin (second choice), or you euthanize her (I use the term "humane" loosely here... I'd never actually want someone to do this for something as treatable as diabetes but if you're going to stare at her till she slowly waste away to a horrible and sickly death at least this is quick and painless). I'm sorry to be so blunt but diabetes is not going to wait and your cat is supposed to be your best friend not a lab experiment. There have been enough lab experiment cats killed to build our understanding of this disease, don't let yours become another! One last note insulin wouldn't "disturb the trend" it would catalyze it and really get things moving.
https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(13)61108-3/fulltext
That may be the single most idiotic thing I've seen in all the time I've been here. Now I know why your vet had you sign a legal waiver.