The communication between the App and Sensor during an activation scan is a short range Near Field Communication (NFC) method which makes it difficult to interfere with or intercept during transmission.

The communication between the App and Sensor for glucose data is a standard Bluetooth Low Energy (BLE) connection. 

The radio frequencies it operates in are: 2.402-2.480 GHz BLE; GFSK; 4.6 dBm EIRP

Bluetooth devices are extremely low powered, typically about 2.5mW which is less than a cordless phone and approximately 100 times less than the maximum power of a mobile phone.

The safety of radio waves has been extensively studied for more than 50 years. This large and growing body of research has been reviewed by numerous independent expert panels, government agencies, standard-setting organizations and health authorities from around the world. All have reached the same general scientific conclusion: that there is no established evidence of any adverse health effects from exposure to radio waves within the limits applied to wireless communications.

In relation to radio frequency emissions and wireless technology and health, the general conclusion from the World Health Organization (WHO) is;

“Despite extensive research, to date there is no evidence to conclude that exposure to low level electromagnetic fields is harmful to human health”

Summary of health Effects – Key point 6  http://www.who.int/peh-emf/about/WhatisEMF/en/index1.html