Number 31 of my list of 33 Things Your Business Planning Attorney Can Do For You is "Protect Your Company's Confidential Information". 

Your company definitely has confidential information, whether it is a customer list, unique process or a special deal with a vendor.  Your attorney can draft a confidentiality agreement that binds your employees and others from revealing that information to outside parties. 

What happens if an employee violates that agreement?  First, you clearly have grounds to terminate them.  Second, you can demand that the employee compensate you for your damages (which were hopefully defined in the agreement).  In some instances, you might even be able to collect damages from the party who got the confidential information from your employee.

Yes, you might have to go to court and your employee might not have the resources to pay any judgment.  But if you don't have the agreement, your employees can claim ignorance and you won't have any recourse against them.  The mere existence of the agreement will signal to your employees that you take this seriously.  And if you have to discipline or sue an employee to enforce the agreement, you send a message to all of your employees past and present that they cannot share your secrets without consequences.