I can't really say how my doses vary between Lantus and Levemir because i only used Lantus when i was newly diagnosed and honeymooning and just shortly after the honeymoon. But i do get about 18-20h out of both Lantus and Levemir. I do like Levemir better though, i feel it's more stable for me, and doesn't sting when injecting it. I take Levemir in the PM, and just cover the gap with some extra rapid in the early evening
I'm currently back to pumping though... But i'm planning to switch back to Levemir and Novorapid again pretty soon. I don't like to wear the infusionsets when it gets too warm, i get itches from the adhesive when it gets mixed with sweat

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22 years old, diagnosed T1D on october 14th 2004.
On MDI, Novorapid and Levemir, using the NP4
Currently back to pumping with my IR1200, April 2008.
Been using D-tron and Animas IR1200 but prefer the pen