Was that your GP that dvised you to wait it out? Have you had any sort of pelvic exam by her yet? My personal opinion is that it can never harm to see a gyno who can judge best what's going on here, so I would personally recommend that you get a second opinion here from a gyno. Just seeing someone to check up what's going on (or not going on, rather) doesn't mean you *have* to start medication, it just means that you will know for sure what's happening. Periods can not be there for lots of reasons, and all should be checked out.
In case your gyno indeed wants to put you on any sort of medication afterwards, make sure (s)he knows your full medical history (but with you being diabetic, I bet you're a pro at giving good medical histories and all the necessary info) and that you discuss it with your normal GP, too.
Hope this helps a little.
~spanking new Scarleteen Sexpert~
"We must become the change we want to see."