The packaging for Medtronic’s pump sites states that you should change them every 48-72 hours. I’ve never been particularly good at sticking to this, sometimes making it as far as 6 days before changing it. I didn’t seem to have any issues with infection or irritation of my pump sites, so I tended not to worry about it too much, as it didn’t seem to have a noticeable impact on my blood sugars.
Since my control has improved, I have noticed a much bigger difference when a pump site starts to get old. Over the weekend I let a pump site get to about 4.5 days before changing it. During the last 24 hours or so before it changed the site my BG levels were noticeably worse, running at 8-10 when I would usually be 6-8. I suspect that it has always had this sort of effect on my blood sugar, but because my control was poor I didn’t really notice the difference between 15 and 17. From now on I’ll have to be more careful about how often I put in new cannulas.