This might sound like a stupid question but I'm just curious. I have been told that one cannot use the vial of Lantus after 28 days?

I gather it become inert or something like that?

Why?

The reason I ask is that it would be much easier for me (even though I label the vials and they are in my fridge), well, it would be easier if I could start a new vial on the first of the month. Much easier.

Is there really a reason why I can't do this?

I mean we are talking 31 days or 30 days in a month, so would those two days really have me using an inert product? I find it very hard to believe that if I am taking my 8 units for 28 days and the 29th day comes and BAM, it's not working any more? Hard to believe.

Thanks much if anyone knows the answer or has even done this themselves.

Melody