The market for health-tech wearables continues to grow healthily. At the end of last year, Fitbit reported more than 25 million active users (an increase of 9 percent year-on-year), with an increase roughly similar for Apple Watches. As the market expands, providers of wearable fitness trackers are starting to aggressively target corporate clients on the strength of new research, showing that the more active employees are, the healthier and more productive they become. A study conducted by Rand Europe for Britain’s Healthiest Workplace shows that employees of all ages can reduce work impairment by 3.2 days a year if they go from no exercise to 150 minutes per week.

According to a survey on global attitudes to workplace benefits done by Willis Towers Watson, a staggering 51 percent of employees in developed economies and 71 percent of employees in emerging economies use fitness trackers or smartphone apps to manage their health.

Take the case of Vitality, an insurance and investment group (with 8.4 million clients in 18 countries), that was one of the first to offer discounts on life and health insurance to policyholders who could prove they took regular exercise and agreed to share data in the process. Vitality has now decided to go one big step further. It is now offering a similar wellness incentive for investors. They’ll pay lower fees in its new pensions and savings products when they can demonstrate that they are living a healthier life.

But the boom in wellness wearables is fueling new concerns over data privacy and security, particularly when insurance companies offer their clients discounts when they upload information about their physical activity. In Europe, the implementation of GDPR (General Data Protection Regulation) that just came into effect will restrict the way in which businesses collect and store information. It is likely to make employers globally more cautious about wearables.

In the wellness space, this a must-watch issue.