Late hubby was on insulin and about 7 pill perscriptions for our last cruises. Re: air & cruise line: It is best and recommended all perscriptions be carried in your carry on luggage in ther eoriginal containers showing the pharmacy applied labels. This includes perscription analgesics and syringes. The ship can and will provide a sharps container for used syringes. Just ask your room steward. Yes, carry on was checked at aiport check in but no questions on shjiop boarding. A note from yr DR on perscription pd or letterhead does also help. Most TSA employees can read and have passed at least their GED these days.
I have to carry an Epi-pen, and have only been hassled about it once at an airport. Since then, I take a letter from my MD explaining what it is and why I need it. I've never had to show the letter, but feel better having it.
never, ever, never pack your daily drugs in your checked baggage, what happens if your bags get lost. Put them in your carry-on, in their original prescription containers is the best, if that's not practical, bring a copy of the prescription. A doctors note for the syringes might even be required, not sure, but its a good idea to bring it along.