Hi,
I've traveled to the US and Canada and the other direction Egypt since Dxd....
The most important thing to remember is the time differences when travelling with insulin. Knowing how to adjust the insulin for the time difference. I always forget and just suffer for a day or so, but im sure it's not what most people want to do...
Also, the only people i would feel the NEED to tell about my diabetes would be maybe the cabin crew on the flight... some people might prefer to have their "diabetic" inflight meals. personally i prefer to eat the normal regular stuff.
Even at the airport i've never had any troubles at security concerning my needles and meters and insulin pens. The first time i flew out to Canada was 3 weeks after dxd and i did tell them then. they didn't seem bothered. On the next few flights i didn't bother to tell them and i've never had any queries about the needles through the X-ray machine. (i can't decided if that's worrying or not!)
Eating abroad is fun, i dont let being diabetic interfear with the experience of trying new foods in different countries and cultures.
All in all, i personally like to try and be as normal as absolutely possible while im on holiday traveling abroad. If people ask, ill tell, but i dont make a fuss of it.