Humulin N Pens

I was reading in the Humulin N pens leaflets that you are supposed to chuck after 2 weeks, regardless of the amount left? Anyone have luck keeping for longer? Seems silly for me since I am using not very much at the moment. I would think it would last as long, if not longer that the Apidra. PS - I am on NPH as we are trying to get pregnant, and had to come off other meds.

when i used pens, i discarded them after 4 weeks of starting use. this was advice from another insulin dependant diabetic and not the manufacturing company. however, there were times i believed the integrity of the insulin was weakened and i would have to use more insulin than normal or i would start a new pen (but the $$$$$). summertime heat and humidity would often be the biggest factors. good luck!