Hi Ashley
I fly to New York every other month or so, normally for about 1 week each trip and this has always been a concern for me, though less so now being on a pump... A bit of maths is involved, you need to work out (approximately) what your hourly consumption of Levemir would be over a normal 24 hour period, for you around 1 unit I reckon? So a 4 hour time difference means that for your outward journey you'll theoretically need to add 4 units to your 24 hour dose, then on the return journey subtract the same amount.
I would leave your morning dose at 14u, maybe have your normal evening dose of 8u around 6pm local time (a little bit earlier than your body "expects" it), then have another 4u just before retiring, assuming of course you can stay awake that long! For subsequent days you're then adjusted and can maintain your normal routine. Coming back do the opposite by reducing your evening dosage by 4u but leaving everything else the same. Hope that makes sense?
Have a great trip :mrgreen:.