I waited to post until this happened to me 3 times. My last 3 newly opened Tresiba pens have lasted 10 days each before losing all effectiveness. I had another night of my CGM alarms alerting me of highs. I am tired of taking correction doses of Novolog throughout the night. The same thing happened last night.
I am used to Tresiba working and working well and have used it approximately 2 yrs.
I am so used to it working well that it has taken 3 different pens to convince me that something is wrong with the insulin.
I am emailing Novo Nordisc.
I may have to switch back to Lantus which worked well for me, but I liked Tresiba a bit better. I am very disappointed.