You can get Humulin N over the counter through the pharmacy (dont need a prescription)
I had started my cat on it and at Walmart the cost was lower than other places (like half the cost at about $25)
Its a fast acting insulin.
But I did not have good results with it. Alot of people do tho I guess.
With my cat her BG levels went from real high, to real low, then would shoot way high again. It was not the insulin for her at all.
Alot of people use PZI, which I think you need to have your vet order.
I started my cat on Lantus at the beginning of September because I read here alot of people have had good results with Lantus and Levemir.
You need a prescription from the vet to purchase the Lantus and Levemir.
I paid $108 at walmart for the Lantus 10ml vial. And I think the Levemir was $118.
Some people order their insulin from Canada and pay less I read.
After its open, the Lantus's expiration date is about 30 days (sometimes lasts longer) so instead of buying the 10ml vial (and throwing half of it away), most get the package of 5 of the 3ml pen cartridges. You would still use an insulin syringe because when you raise the dosage, its at .25 units each time. The Pen has only whole numbered units on it.
The protocols say to start low like at 1 unit. And you have to go by the protocols and slowly work your way up until you figure out the right dosage. Its a slow process.
It is a slower acting insulin, rather than fast acting like the Humulin N.
Go to each Insulin Support and read the sticky's near the top of the messages. Especially the protocols and the Storage Shed/Insulin Depot on the lantus page.
You will need to test your cats Blood Glucose level, so you will need a meter and supplies.
Everyone sets up a Google Docs spreadsheet to monitor those readings. See below for the link for mine.
Most everyone here uses the human meters you can purchase anywhere. If your vet tells you that you can only use a pet meter, its not true. Blood is blood. That is just what some vets believe.