Where or if you do a fellowship depends alot (but not entirely) on where you did your residency training. There are DO's from DO IM residencies now matched into allopathic fellowships, and there are DO's who do allopathic residencies and subsequently match into allopathic fellowships, both at their institution of residency and elsewhere.
Endocrine is not considered to be the most competitive fellowship to procure (not dissing on endocrine, and of course there are exceptions to this generalization). For what that's worth, it may help in your selection of WHERE you do your residency (e.g. community-based program versus university hospital-based program. The latter do tend to have more research faculty, and therefore more research opportunties to do while in residency. This may not seem like a lot right now but may when the time comes for you to apply to fellowship programs in endocrinology.
my $0.02
