I must say I belong to the latter (endocrinologist). If I had to pick an area (really, outside of a really academic institution, this isn't feasible) I'd consider myself a thyroidologist. That's been my area of research, and primary area of interest. Diabetes, sure, I could handle. After all, in my world that's going to be the bread-and-butter, but that's not where my passion truly lies.
Workwise, I've seen a fascinating number of cases this week. I've been coming home pooped, but yet intellectually stimulated. From pituitary apoplexy to autoimmune polyglandular syndrome type 2 (Addison's disease and premature ovarian failure) to adrenal incidentalomas to 4 hypo_glycemia patients (of which two are real, after gastric bypass, which brings my personal total to 18). And I diagnosed papillary thyroid cancer in one patient and biopsied two benign thyroid nodules too. And while I was mostly lost and overwhelmed 2 years ago, it's now become fun when I'm the PGY-6, senior fellow, and I actually know what I'm doing half the time (as compared to <10%).