I am a Type 1 diabetic and fly with insulin and supplies. I always just put them in the quart ziplock for fluids and send them through the scanner. Last time I forgot to take the ziplock out of my bag and they didn't notice it, but usually I make it clear.
I always carry snacks for lows, especially at WDW. I have seen others mention using bolus doses of about 3/4 of normal just due to all the activity at WDW, and that seems like a good start. Otherwise you will be perpetually chasing lows.
I have also seen posts that suggest not making any note of diabetes on your reservation. I am not sure why you would note it, but leaving it off makes sure that you can manage your meal choices and not be told that the poor kid can't have sugar.
I hadn't seen the Frio packs before, but I am ordering one for my next trip. Another benefit of the DIS boards!