Are there things besides just thyroid & diabetes, that an endocrinologist treats? another dr. suggested that today for extreme sweating!

Yes: Endocrinologist deal with problems of hormones and glass diabetes and thyroid are the most common. Extreme sweating can be due to a thyroid imbalance or other hormone problem.

All hormones: Yes, an endocrinologist treats all hormone issues include high and low testosterone levels, parathyroid hormone issues etc. Since excessice sweating often has a hormone basis, it is reasonable to see an endocrinologist for this problem.