I started using Apridra in January, hoping to have a faster post-meal "kick-in" time with this insulin. I struggled for 6 months with Apidra, finding that it worked OK the first two days in the Minimed Paradigm 523 pump but lost its effectiveness beginning on the 3rd day (but that took months to figure out it was the insulin and not me or the pump). I switched to Novolog. Yippee- it has lasted into the 4th day (haven't tried any longer). I notice the lowering of my glucose begins within 30 minutes of taking it, and peaks at about 2-2.5 hours. This is very comparable to the Apidra, except Novolog's life in the reservoir remains vibrant. This has been a good and necessary change for me! I wonder how many other Apidra users think something has gone wrong with their pump or their body, when in actuality it is the short out-of-the-vial shelf life?