The interest in Machine-to-Machine (M2M) systems has grown in recent years due to ubiquitous wireless availability and declining prices of communication modules. Although in some areas this concept has developed adequately, e-Health is not one of them. The European Telecommunications Standards Institute (ETSI) has made great efforts to develop standards in this field, but the resulting documents are sometimes difficult to understand and include extensive technical information. The first objective of this research is to place the M2M architecture defined by ETSI in the environment of e-Health, identifying theoretical concepts with real situations and specific devices. Then, our work analyses use cases of M2M applications for e-Health defined by ETSI, clarifying ambiguous situations. To review the use cases, we use a personal and simplified scheme for the architecture that is based on a vertical and horizontal model, which allows a visual and intuitive interpretation of the steps executed in the different scenarios. The engineers will have several diagrams with interacting entities that represent a very useful aid for system design and implementation. In the review, we also find the importance of energy efficiency in e-Health, especially in life-critical applications, which may be the subject of further investigations. On the other hand, our study reveals the main problem with medical devices: the plurality of communications protocols established by suppliers. The current ISO/IEEE 11073 standards, which enable interoperability between these devices, may be a good starting point to achieve M2M standardization in this area.