I’ve cruised with Reta, Sema, TA-1, and Klow over the past year with no issues at all. Before switched to pens, I would put vials, syringes and alcohol pads in a thermos with an ice pack designed for insulin. Now that I switched to pens, I usually keep the needles and alcohol pads in a separate bag because the container only holds 2 pens. I’ve brought them to Italy, Spain, Switzerland, the Netherlands, Belgium, France, Florida (Miami and Fort Lauderdale), New York, Mexico, and San Juan. Not once was I asked about them at airports or at cruise ports. I always keep the container and supplies in my carry on.
TSA will sometimes be a little curious and send my bag for secondary screening, but the moment they see a syringe or a pen, they put the lid back on and send me on my way. Never have I been asked what’s inside.