Keep your insulin and supplies in your hand luggage and if travelling with a partner split them up between you both in case one bag gets lost. Before travelling check with your destination if the accommodation has a fridge in the room or one you could hire to keep your insulin cool, also ask your gp/consultant for a letter to say that you have diabetes and it is treated by insulin to show at the airport if asked.
Just in case of emergency's take along a copy of your repeat prescription, if you need anything you can present this to a Dr or take it along to a pharmacy so that show what meds you take, Frio wallets are great for keeping insulin cool whilst travelling out and about during the day.
The heat can make you very sensitive to insulin and you'll more than likely find you'll need less, checking more often than normal in the first few days would be advisable until you know what effect it has, if travelling to a cold country then the opposite might apply.
Last of all enjoy the break and don't stress too much, a bit of pre-planning goes a long way and saves a lot of hassle when you get there.