Hi Acron,
You will probably be put onto a basal insulin in the future, but if your premix is working thats great.
Splitting is when a basal insulin ie Levemir is split into 2 dosages. One before bed and one in the morning. Not everyone does this, as everyones requirements are different. My son is on Levemir and takes 20u before bed, but if he did required to spit his dose, it could be done. I know Fergus uses Levemir and splits his dose, 50/50
Hope this has helped with your query.
Suzi x