The BRIGHT Study (Device Name: HALO System)

The purpose of the BRIGHT study is to evaluate safety and performance of the HALO SYSTEM in subjects with diabetes mellitus. The primary objectives of this clinical investigation are 1) the evaluation of sensor's performance by demonstrating sensor's accuracy and stability and 2) to confirm safe implantation of the Sensor and safety of the device during implantation.

Inclusion Criteria: * Willing to sign an informed consent form * Age ≥ 18 years * Willing to comply to study protocol requirements (study visits with frequent venous blood sampling and deliberate insulin, glucose, ketone and lactate challenges) * Willing to charge the SENSOR on daily basis * Willing not to insert their standard CGM and/or insulin pump in and around the SENSOR implant site (± radius 5 cm)\[TS\| XR1.1\] Diagnosed with type 1 diabetes mellitus according to the World Health Organization criteria, for at least 12 months prior to screening, on CSII therapy Exclusion Criteria: * Known allergy to polydimethylsiloxane (PDMS) * A contraindication to undergo challenging tests (i.e., ischemic heart disease, epilepsy, panhypopituitarism, hypoadrenalism, untreated hypothyroidism) * History of hepatitis C or HIV or other disease transmissible by blood * A condition requiring or likely to require magnetic resonance imaging during the study duration * Female participants who are pregnant, planning on becoming pregnant or nursing * Coagulation disorder, wound healing and bleeding disorder or taking anticoagulant medication (oral anticoagulants; antiplatelets (such as aspirin, ticagrelor are allowed). * Anemia identified by a haemoglobin \