Our six-year-old was diagnosed with type1 diabetes earlier this year and this was our first trip back since. Despite some initial worries everything went fine. We had no dramas whatsoever with officialdom re: the amount of syringes/drugs we had with us (like enough insulin to kill five elephants etc.) In fact, nobody official either in Oz or Bali asked once what it was all for.
The only problem we did have was with the timing of meals. The kid has to eat at around the same time every day. This is a bit hard to do when you're tripping around the island (and there's an hour and a half time difference). We got around this by packing meals for him to take with us and doing extra Blood Glucose tests throughout the day to keep a closer eye on his levels. Bit of a pain but it prevented any major dramas.
One thing that was a major concern - which we thought may have been related to his diabetes - was that his fingers and toes started bleeding whenever he spent a bit of time in the hotel pool. Very weird. We'd already booked to see his pediatrician when we got home, just to make sure everything was okay. The doc said the bleeding was more likely to have been from some viral infection rather than the diabetes. Bit hard to say where he got it, here in Oz before we left, or in Bali when we got there. Anyway, it's stopped now and all is good.