What makes the hands sweaty?  There are a few known causes:

A hyperactive thyroid
Anxiety
Heat
Overactivity on the part of the person
More sweat glands in the palm than normal
Hyperactive sweat glands.

Whatever the cause, the end result is the same: an unpleasant feel on the part of the recipient of the sweaty hand shake, and embarrassment on the part of the man who has his hands sweaty.
It is because of this that there are all sorts of sweaty palms treatment offered in the market.
A hyperactive thyroid is of course treated if one cures the hyperactive thyroid gland.  This will obviously cure sweaty palms related to hyperthyroidism.
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The other causes are rather more challenging to treat.  Some more well known methods to treat, though not necessarily cure sweaty palms are:

1.  Constant wiping with handkerchiefs

2.  Application of chemicals that are said to suppress sweat gland function eg Driclor (ammonium chloride hexahydrate).  The tendency is for this to become less and less effective over time.

3.  Surgery – a procedure called thoracic sympathectomy whereby the nerves of the sympathetic nervous system in the chest cavity which control the sweating palms are destroyed.  Although this is about the only permanent way to control sweaty palms, soles and armpits, a lot of people balk at the thought of surgery just to stop sweaty palms.

Botox Injections For Sweaty Palms

4.  Injection of Botox.  A very effective technic to cure sweaty palms.  Although the effect lasts only 1 year and needs to be repeated, it is considered a very acceptable and suitable alternative to surgery which may carry some risks. The procedure is simple in theory.  Under local anesthetic botox is given in multiple small superficial shots on the palm about 1cm apart and just under the skin  (not into the muscles of the palm).  The fingers are usually left alone as a degree of moisture is essential for a good grip.  Treatment results for hands sweating are usually considered satisfactory if done properly.