You must carry a copy of a letter from your doctor which you may need to show Customs. The letter should outline any medical conditions, any medications you take and the devices you use for your insulin and blood glucose testing, such as insulin pens, syringes and needles or pump unit.
Also take the medication packaging with your name on the box with you as well.
Instead of packing a cooler with traditional ice packs, which need to be refrozen when they get warm, pick a cool pack, such as those made by Frio, that doesn't require freezing or refrigeration. Just run it under cold water for five to 10 minutes, and crystals in the pouch will keep insulin cool for hours.