Hi everyone. I wonder if this has happened to anyone and if so what might have caused it. I injected my Lantus as usual this evening. I expelled the air as always by shooting 2 units into the air. As the level of insulin was going down I noticed blood had gotten inside the transparent part of the pen. This has never happened before and I cannot work out why. It was not a new pen so it must be my blood and it had just happened else I would have spotted it before. Good weekend to everyone, thanks, Carole