Real-time converter of intermittent-scanned glucose sensors to continuous glucose monitors with potential future applications for insulin delivery

Abstract

This paper presents the development of a transmitter that transforms intermittent glucose sensors (isCGM) into a continuous and real-time glucose monitoring system (c-rtCGM), a key component in automated insulin delivery systems. The transmitter enhances the capabilities of conventional intermittent sensors by leveraging Near Field Communication (NFC) technology to capture raw glucose value and automatically transmit it via Bluetooth Low Energy (BLE-Bluetooth 4.2 Dual-Mode) to a smart device every five minutes. A specialized glucose monitoring application converts the raw values to blood glucose by applying a calibration based on a static linear model and a capillary blood glucose measurement. The accuracy and performance of the c-rtCGM were validated through a study involving 37 participants with type 1 diabetes, demonstrating its reliability compared to commercial transmitters. Values reported by the c-rtCGM system compared with the isCGM monitor system resulted in an overall mean average relative difference (MARD) around 9%. During the trial, the c-rtCGM system achieved a data transmission success rate of 96%, and only 2316 connection failures were recorded from the 66525 total connection attempts, indicating a high level of communication stability. The transmitter battery life lasted an average of 6.5 days, showing that it is necessary to recharge only once for the duration of the sensor (14 days). The main advantages of this customized transmitter, in contrast with the commercial versions, are reliability, cost, and the flexibility of its software, since its processor (an ESP32) can be easily programmed to fulfill other helpful tasks in managing glucose levels with automated insulin delivery systems.