Continuous Glucose Monitoring (CGM) systems improve glycaemic control in type 1 diabetic patients but they have different characteristics that could influence patients' quality of life and glycaemic control.

In this randomized cross over study investigators will compare 2 different CGM systems: Eversense implantable sensor (Senseonics, Germantown, MD, USA) and the standard transcutaneous sensor Dexcom G5 (Dexcom, San Diego, CA, USA). Investigators will evaluate sensors' accuracy, impact on quality of life and efficacy in optimizing glycaemic control.

The investigator's study's results might help clinicians choose the sensor and evaluate how sensor differences could impact glycaemic control.

Good glycaemic control in type 1 diabetic patients prevents the onset and progression of chronic complications. Continuous Glucose Monitoring (CGM) systems help patients improve glycaemic control by providing real-time glucose levels, glycaemic tendency, glycaemic swing rate and by alerting the patient when the glucose value read by the sensor reaches a predefined threshold of hyper or hypoglycaemia.

Several CGM systems are available and they have different characteristics that could influence patients' quality of life and glycaemic control.

In this randomized cross over study investigators will compare 2 different CGM systems: Eversense implantable sensor (Senseonics, Germantown, MD, USA) and the standard transcutaneous sensor Dexcom G5 (Dexcom, San Diego, CA, USA). Investigators will evaluate sensors' accuracy, impact on quality of life and efficacy in optimizing glycaemic control.

Patients will use Dexcom G5 or Eversense for three months, respectively, in a randomized order. Accuracy will be evaluated comparing sensors values with capillary blood glucose at home.

Quality of life will be assessed at the beginning and at the end of each three-month period through validated questionnaires to underline differences in different sensors use.

Time spent in target (70-180 mg/dl), in hypoglycamiea and hyperglycemia will be evaluated with both sensors to assess differences in glycaemic control induced by different alarm system and by the presence of predictive alarms

Inclusion Criteria:

• Male and female participants of at least 18 years of age
• Diagnosis of type 1 diabetes mellitus (diagnosed according to World Health Organization criteria) for at least 1 year
• Body Mass Index (BMI) <35 kg / m²
• Availability to wear study equipment and to comply with the study protocol for its entire duration
• HbA1c <10%
• Signature of informed consent before any procedure related to the study.

Exclusion Criteria:

• Pregnancy, breastfeeding, intention to undergo pregnancy or refusal to use contraceptive methods during the study period (for female subjects).
• Known allergies to skin patches or disinfectants used during the study.
• Skin lesions, irritation, redness, edema in sites where sensors can be applied, as this might interfere with sensor's placement or with the accuracy of the glycaemic value detection.
• Use of drugs that may interfere with glucose metabolism (such as steroids) unless they are chronic therapies whose dosage has remained stable over the past 3 months and is expected to remain stable during the study period.
• Use of acetaminophen or other drugs that could influence sensor accuracy
• Severe medical or psychological conditions, which, in the opinion of the medical team, may compromise patients' safety while participating in the study.
• Patients enrolled in other clinical trials.
• Known disorders of adrenal glands, pancreatic tumors or insulinoma
• Patient's inability to comply with the procedures of the study