Why do you hate fu'ivla? And why do you say that the ability to define something in Lojban mandates us to do so?
Diabetes is a domain specific term. Personally, I find it strange to come up with lojban-specific names for things in specialised domains such as regional cuisine, cultural references and scientific terms. Medical terms are one of those things for which we're lucky to have had a scientific crowd contributing a huge, mostly unambiguous, clearly defined, and undisputed vocabulary with relatively descriptive names from its language of choice. They've done a pretty good job with it already. There's already basically a consensus and we'd be the only ones upsetting it. I don't see what we'd win out of reinventing that wheel.
The clear drawback is that we create more work for ourselves defining a comprehensive vocabulary, and learners get hit with more work having to learn a new, unfamiliar word. Best case they just ignore the word and use a familiar cmene anyway and your effort is lost. Worst case is the whole community learns the new word and the cost is paid once for every learner. I feel the cost of inventing a brand new word needs to be weighed against the benefit. I can see the benefit for ideas which have many very different words in many different languages, but science, medicine, and cultural terms just don't seem worth it.
I don't want to be a killjoy. I can see the sense in doing it just for fun. But I don't like the idea of foisting redundant vocabulary upon the whole community.