I am not diabetic, but don't like to drink calories (since I love desserts!) and am allergic to aspartame. I can have drinks with Splenda. RCCL has a strawberry kiwi drink offered free in the Windjammer with the lemonade/tea/etc. (but they don't ever indicate that it has Splenda so you wouldn't know unless you needed to know). I was curious if Carnival has an equivalent but from this thread it sounds like they don't. I always carry a 12 pack of Diet Rite and a berry Mio which adds flavor and caffeine. I also bring powdered Gatorade Zero packets and a reusable 20 ounce water bottle to mix them in. So, you could either of those options and just add a shot to it. The Mio and Gatorade Zero are usually always available online from Walmart.