### Communications Environment  
In order to connect the IoT devices to the cloud for the processing of data, it is essential to provide a communications infrastructure with channels for transmitting a large amount of data. In this way, nowadays, the connection possibilities have been expanded and it is possible to find a wide range of ways to transmit information. Providing devices with a Wi-Fi transmitter can open new perspectives that will allow an increase in connectivity between medical equipment. However, out of the range of a Wi-Fi net, which can be available in a patient's home or, for instance, in a hospital environment, it will be necessary to rely on a smartphone 4G connection to launch data to the cloud. In any case, it is possible to provide self and independent connections to every device through its own SIM cards.  
The communication between the devices can also be based on Bluetooth, which, in the form of BLE, is a promising way to gather information. This is the communication technology proposed in the architecture presented in this paper. BLE has been designed taking into account the requirements of the IoT, allowing for the transmission of data without the need to establish a connection, so that the pairing and transfer are faster (3 ms). Therefore, in a discrete transmission, sensors can sleep and wake up periodically to transmit, which involves a saving of energy. BLE is able to develop several functions, from the gathering of data to remote management.  
Other types of connections are also interesting alternatives. ZigBee is an IEEE 802.15.4--based specification for a suite of high-level communication protocols that are used to create personal area networks with small, low-power digital radios, such as for home automation, medical device data collection, and other low-power low-bandwidth needs that are designed for small-scale projects that need wireless connection. It is intended to be simpler and less expensive than other wireless personal area networks (WPANs), and it is able to connect more than 65,000 nodes with a lower energy consumption because the nodes can go sleep when they are not in use. However, in our case, that number of nodes is not necessary and the sensors cannot be deactivated because monitoring is carried out 24 h per day.  
On the other hand, NFC is a set of communication protocols that enable two electronic devices to establish communication by bringing them close to each other. By now, this technology is in use in the Abbott Freestyle Libre CGM device. Another possibility can come from ANT+, which is a wireless technology that encourages interoperability and open access to data between different manufacturers of smartphones, diagnostics, power meters, heart rate monitors, remote control systems, and so on.  
In view of the above, it can be noticed that different problems regarding the interconnection between all of the devices involved in a smart diabetes monitoring system could arise due to a lack of communication compatibility. Such fact has been properly analyzed in [14]. Furthermore, it should be noted that the proprietary software/protocols and the companies policies could also represent some barriers in the creation of an integrated system In this sense, it is fare to mention the efforts of the Nightscout Project [36], an open source, \"do-it-yourself\" project that allows for real time access to a CGM data via personal website, smartwatch viewers, or apps and widgets available for smartphones. It was developed by parents of children with DM1 and has continued being developed, maintained, and supported by volunteers.