When they first start you out they go by a certain amt. (i have not had adequate medical care since they started me on insulin and my levels never go down enough but I cant afford to go to drs.) then they teach you how to give to yourself the amount for the level of sugars in the blood. I havent went to that stage yet cuz no medical care so I just keep taking 35 units in the am, 32 units in the pm. But like I said mine never goes down far enough. It has been 2 years since insulin introduction--i was taking oral meds for it they never worked.