Global shipments of wearable devices came to 18.1 million units in the second quarter of 2015, up 223.2% from the 5.6 million shipped a year earlier, according to IDC.

Fitbit ranked as the number one vendor with shipments totaling 4.4 million units in the second quarter, up 158.8% on year, but its market share dropped to 24.3% from 30.4% during the same period, IDC said.

Apple's wearable device (Apple Watch) shipments totaled 3.6 million units in the second quarter, positioning itself in second place and accounting for a 19.9% share.

Xiaomi Technology shipped 3.1 million in the quarter for a 17.1% share, followed by Garmin with 700,000 units or 3.9%, and Samsung Electronics with 600,000 units or 3.3%, the data showed.