Investigation of a long-term continuous glucose monitor in type 1 diabetes

This study is designed to provide frequently-sampled data from an investigational long-term continuous glucose monitor to optimise signal processing techniques and improve sensor performance. The investigational device is a subcutaneously implanted metal sensor about the size of a large USB that is designed to measure interstitial glucose levels. The sensor contains a small battery and a transmitter that wirelessly transmits data from the device to a handheld receiver and is stored in the receiver’s memory for later download and processing. It is fully implantable i.e. nothing is worn on the skin and will remain in-situ for approximately 4 months. It will be implanted into the subcutaneous tissue of the lower abdomen by a qualified surgeon under local anaesthetic and light sedation. Following implantation, the sensor requires no user interaction or maintenance, although the receiver needs to be kept close by to ensure that data packets are reliably recorded. The only maintenance required for the receiver is battery changes and download of receiver data. Participants with type 1 diabetes will have the device implanted under local anaesthetic and will undergo weekly clinic visits during the 4 months of implanted sensor wear. Additionally, participants will undergo four meal-driven glucose excursion visits where hourly capillary blood finger-prick and 15-minute venous blood glucose sampling will occur for up to 8 hours. Once per month, at one of the weekly visits, participants will be asked to wear an activity tracker and to complete the standing and sitting activity over a 1-hour and 15-minute period. Finger-prick glucose measurement will be performed before and after the one hour and 15-minute data collection. Between clinical site visits, participants will carry a data logger receiver that records signal outputs from the implanted sensor (display shows date/time, but no glucose information), change the AAA batteries in the study receiver daily and confirm the receiver is receiving data, self-monitor blood glucose (SMBG) a minimum of 4 times per day, respond to daily text or phone call confirming the receiver is working with an appropriate date / time and record study activities in a participant diary. Trial participants will be provided with a commercially approved continuous glucose monitor (CGM) for use during the study and participants will be trained on the use of the CGM by the study site. Participant data from the CGM (de-identified) will be downloaded during the monthly in-clinic visit. Explantation of the sensor may occur immediately following the final meal excursion visit or up to 4 months and 20 days from the date of implant. The explantation procedure, in general, mimics the implantation procedure and is performed under local anaesthetic.