Continuous glucose monitoring system The glucose sensor that will be used throughout the clinical studies is the Dexcom sensor (CE marked, manufactured by Dexcom). This current is proportional to the glucose concentration in interstitial fluid and is calibrated against blood glucose a minimum of 12-hourly. The Dexcom CGM data is automatically transmitted to a secure web-based server and the secure PEPPER web-portal. Participants will be able to see their CGM data at all times and this will be used continuously throughout the studies.