Randomized Trial of the RIGHTEST iFree 2 CGM System for Glycemic Control in Adults With Diabetes Mellitus

1. Subject is ≥18 years of age at the time of enrollment.
2. Subject has a confirmed diagnosis of type 1 diabetes mellitus (T1DM) or type 2 diabetes mellitus (T2DM) for ≥1 year.
3. Subject has an HbA1c between 7.5% and 12.0% at screening.

4. Insulin therapy requirements by cohort:

   4.1 T1DM: On multiple daily injections (MDI) or continuous subcutaneous insulin infusion (CSII) for ≥3 months prior to screening, with no major adjustments in insulin dose or regimen within 8 weeks before screening.

   4.2 T2DM: On insulin therapy for ≥3 months prior to screening, defined as one of the following regimen classes: (a) Basal-only, (b) MDI (basal + ≥2 prandial injections/day), (c) CSII, or (d) Premixed insulin (≥2 injections/day); with no switch across insulin regimen classes and no major insulin-dose adjustments within 8 weeks before screening.

5. Subject is willing to comply with all study procedures, including CGM wear during the run-in period and follow-up visits.
6. Subject has access to and is able to use a compatible smartphone (if required by the CGM system) and is willing to install and use the study application.
7. Subject is able to read, understand, and write in Mandarin.
8. Subject is willing and able to provide signed written informed consent prior to any study-related procedures.
9. Subject has successfully completed the blinded CGM run-in period of at least 14 days (target 15 days) with ≥70% valid sensor wear time prior to randomization.
10. Subject remains eligible per investigator's judgment, with no significant change in medical condition or diabetes treatment since screening that would preclude participation.
11. Subject remains willing to comply with randomization to CGM (intervention) or SMBG (control) and complete the 24-week follow-up period.

Exclusion Criteria:

1. Known allergy or intolerance to medical-grade adhesive tape.
2. Presence of unresolved, extensive skin changes/diseases at potential sensor wear sites that would preclude sensor placement (e.g., psoriasis, severe eczema, scarring, tattoos, burns, or dermatitis herpetiformis).
3. Female subjects who are pregnant, planning to become pregnant, or breastfeeding during the study period.
4. Currently receiving or planning to receive dialysis during the study.
5. eGFR \< 30 mL/min/1.73 m².
6. Current use of, or planned use during the study, of any real-time CGM (rtCGM) or intermittently scanned CGM (isCGM) device.
7. History of severe hypoglycemia (requiring third-party assistance) or diabetic ketoacidosis (DKA) within 6 months prior to screening.
8. Anticipated or planned acute use of glucocorticoids (oral, injectable, inhaled, or intravenous) that may affect glycemic control or HbA1c.
9. Any condition that may affect the accuracy of HbA1c measurement within 3 months prior to screening (e.g., recent blood transfusion, erythropoietin therapy, hemoglobinopathies).
10. Implanted cardiac devices such as pacemakers or implantable cardioverter-defibrillators (ICD).
11. Critically ill subjects, or those with medical or psychiatric conditions that, in the opinion of the Investigator, may pose a risk to participation or interfere with compliance.
12. Severe psychiatric illness, substance abuse, or other conditions likely to impair adherence.
13. Any other condition that, in the opinion of the Investigator, makes the subject unsuitable for participation.