Further to what Trudy said, I use three overlapping doses of Levemir to extend the action of the Levemir, but they are not equal sized doses, but 8u +5u +2u at morning lunch and midnight or bed time. The amount of the bedtime dose varies with the blood test level. I don't take insulin without checking first and I adjust the level taken based on the result.
Since they say people on the pump tend to use 75% of what they used with MDI. Did you find you now have to take more than you did on the pump on a TDD (Total Daily Dose) basis?
If they tell you that is just because ....whatever they say, I know it is because the body tends to destroy large doses and that is why large doses are so variable as some days more or less is destroyed. (see DrB's chap 7)
When people talking about cancer treatment mention that the body "walls off" something it doesn't like...that is the same thing with large injected doses and it explains why people develop lumps under the skin from injections, as the body does use cholesterol to plaster over things it doesn't like. That is how tumours develop. Not all tumours grow from the center outwards, but develop because the body is trying to inactivate what it doesn't like.
So even though people do not like to do injections, they WILL if they see an advantage. One woman taking huge injections was getting lumps under the skin with 20u (dinner short acting) and 30u (bedtime Levemir) injections of long acting and 10u for breakfast and 10u lunch of short acting. She is about 220 lbs. I explained that if she did more injections of a tiny size she would solve the problem, but I advised, since I am certain part of your injections are being destroyed, you can NOT do 3x10u instead of 30u as it would then be effectively taking too much...so she first tried 2x12u and it worked just as well, then 3x7u=21 and she is pleased as punch that she no longer gets lumps and her morning blood sugars are just as good.
People believe the body is non thinking, but it is highly programmed. That's why acupuncture works. If you prick the body with needles, it's attention is drawn to that location and it does what it can to heal the area. So if you give large injections, then the body will certainly notice. And analogue insulins are not truly human, they are slightly different. So the reason the pump can be used with less insulin is that a small tiny drip is not destroyed as much.