If you dial the pen to the number of units, insert the needle into your skin and push down the button but THEN (once you've pushed the button down but whilst the needle is still inside you) re-dial an extra unit(s) and press again, will that extra unit(s) still get properly delivered?
I can't see why not but just wanted to double check! I needed 3 units this morning but only dialled 2 and thought I could redial the extra unit without having to pierce the skin again.