Sorry, I don't know how COBRA works at all, so can't offer any thoughts about that...except that I thought that someone on COBRA could get insurance at any time (and drop COBRA), that it was a matter of you HAD to get insurance before the COBRA ran out? (Not...can't get insurance until COBRA runs out)? But as I said before, I don't know anything about it, just what I've heard others talk about.
How are you expecting to get insurance? Private pay? Be ready to pay a LOT...not only because you have a "pre-existing condition" (the diabetes), but simply because it costs a BUNDLE. Do you have a spouse who is employed? Is there any possibility you can get insurance through him?
If your PCP is willing to call it MS...and give you appropriate treatment for it...what is the question? PCP's are able to diagnose MS, and treat it. Some insurance companies demand a neuro back them up...but not all of them do (mine doesn't, for example), so maybe that really isn't an issue after all? If your PCP is willing to treat you...then so be it. I haven't seen a neuro in over 11 years, now.
Anyway, just my random thoughts.
...I am not a doctor, nor health professional, and don't pretend to be one, here.....