The problem is the design. Lantus cartridges don't fit in a Novopen. With Lantus, the needle screws onto the pen (like with a Humalog pen). With Novo, the needle screws ont the cartridges, which are made with a thread on them.
Lantus works fine with a Humalog pen. Because I have been using one ever scince I switched to Lantus two years ago, calibration differences are irrelevant. The calibration may well be a bit dfferent, but as long as you don't switch between different pens, you will get consistent dosing.
