Possible security threat: A wearable is an internet-connected device. The more routes you open up to the internet, the more avenues you are giving a potential hacker to invade your system and to steal data. Make sure any wearable device that can access your data comes fitted with adequate security measures.
Misuse of technology: As the devices get smaller, there is potential loss of control over what employees can do with them. Resentful employees could record activities and share data with outside agencies.