| I know of two occasions when pen cartridges have leaked and caused trouble. Don't get me wrong I love the pens and have been using them for 10 years now. However, I had one occasion last year when my normal BG numbers which range from 3.9 to 7.5 (sometimes spike a bit higher when I have eaten something I shouldn't)....suddenly shot up into the 15 to 21 mmol range. I thought maybe I had some illness brewing, though it got worse day by day. I had noticed some moisture on my hand at one point but thought that I had not dried my hands properly before doing the shot. Finally after about 2 or 3 days I felt this liquid on my stomach, and there was quite a lot of it. I took the pen apart and found that the cartridge had chipped at the base and the pressure was forcing the insulin out of the bottom of the pen, possibly some into the barrel and I wasn't getting the proper amount. Thankfull I was using two types of insulin, so I getting my basal shot of Levemir. Howevery my meal boluses were useless - I was thankful to find out it was a cartridge failure and not me going down with some dreaded lurgy. I must have dropped the pen at some point, but I can't remember actually doing that.
The other occasion resulted in a far more serious situation when my friend was in Florida for several months during the winter and she was on a mix insulin. Her numbers went crazy and were rising up over 20 into the 30's even higher until the meter would not read it. Her husband called an ambulance and she was admitted into hospital very seriously ill - they said her numbers were way up into the 1,000's mg/ml. She hovered in a coma like state for several days in intensive care, but thankfully survived and is now doing very well. It was the same problem that happened to me, and it was only when her hand was too shaky to do her shot and her husband was doing the shot for her that he felt the insulin running over his hand. He checked the cartridge and had the same kind of chip on the base of the cartridge that I had found. Mine was a Humalog cartridge though, and my friend's was a mix. So just a little warning to pen users....if you see some crazy numbers when not expected - do check the cartridge to make sure there is no leak there.
I have never heard of anyone else having that trouble, so it was odd that it happned to two people who knew each other.  | 
