Study of GLUCUBE Performance, a Non-invasive System for Monitoring Blood Glucose Levels Based on Near Infrared Spectroscopy (NIRS) Technology.

Inclusion Criteria: 1. Be ≥ 18 years old. 2. Have a smartphone with an internet connection that allows the installation of GLUCUBE APP 3. Have signed the informed consent. Exclusion Criteria: 1. Subject is currently participating in another clinical investigation or has participated in another clinical investigation in the past 30 days prior to the start of the present study. 2. Pregnant or nursing subjects and those who plan pregnancy during the clinical investigation follow-up period. 3. Presence of other anatomic or comorbid conditions, or other medical, social, or psychological conditions that, in the investigator's opinion, could limit the subject's ability to participate in the clinical investigation or to comply with follow-up requirements, or impact the scientific soundness of the clinical investigation results. 4. Patients with any acute active and/or infectious disease. 5. Patients who have a condition that affects blood circulation in the fingers of the hand, such as Raynaud's phenomenon. 6. Any medical condition that, by the investigator judgment, will increase the risk from hyper and hypoglycemic event: seizures, heart disease, hypoglycemia unawareness, etc. 7. Patients who, in the opinion of the investigator, do not have sufficient manual dexterity to perform the tests themselves. 8. Patients with an inability to maintain stability of the hand during measurement or with progressive disease of the nervous system that affects movement (Parkinson's disease, moderate-severe essential tremor, and other diseases with involuntary movements). 9. Patients suffering from calluses, malformations, or open wounds with bandages. 10. Patients with nail polish or any type of false nail. 11. Subjects who do not understand or cannot follow the Procedures Involved in the Use of the Device Under Investigation.