When I filled up my cartridge the insulin looked a little cloudy.I wonder if that means that it has gone bad.The expiry date was within range.
I have had R insulin go bad. It gets tiny crystals in it.
Things that make it go bad include keeping it in the fridge door which quivers every time someone opens it. The shaking can ruin it, it turns out.
Too much heat.
Introducing contaminants after using it for a long time. I use one vial for several months and it always fades out by the end of the second.
I had a bad vial of insulin today even though it was within range of date as well. Sometimes there is just a bad batch. I knew it was bad because I was fighting for over 12 hours to get my blood sugar down and finally after I decided to try a new vial, my sugar went down.