Internet of Things (IoT) is a network made up of a large number of devices which are able to automatically communicate to computer systems, people and each other providing various services for the benefit of society. One of the main challenges facing the IoT is how to secure communication between these devices. Among all the issues, the Group Key Management is one of the most difficult. Although different approaches have been proposed to solve it, most of them use the same security parameters to secure all communications. Thus, if several services are provided by the network, communications within a service will be accessible to all network members even those which did not subscribe to it. Moreover, the compromise of a member will jeopardize all services. In this paper, we propose a highly scalable Multi-Group Key Management protocol for IoT which ensures the forward and backward secrecy, efficiently recovers from collusion attacks and guarantees the secure coexistence of several services in a single network. To achieve this, our protocol manages several groups with independent security parameters.