Spouse of a type I diabetic here. First off, don't worry -- everything will be fine, and your daughter will have a great trip. Second, if you feel any anxiety about your daughter traveling as a diabetic, do your best not to let on -- it will be easier for her.

- The TSA is really accustomed to people like your daughter going through security, and in my experience generally understanding and courteous. Thousands of diabetics travel every day.

- My spouse always just sends a carryon with all manner of diabetes crap through the xray (including syringes) without saying anything to the TSA and no one has ever asked about it or sent it back through

- He carries a letter from a doctor about the supplies and it's never been needed

- Opting out of scans is easy, when you get to the scanner just say "I'd like to opt out please" to the person waiving you through.

- For a long international trip, my experience is that it's easier to check luggage. Pump gear is really bulky in its packaging, plus your daughter might want to buy cool stuff in Japan to bring home. I'd carry on a few days of supplies and check the rest. Worst case scenario, you can fedex stuff over there.

- Japan has awesome candy for those hypoglycemic moments