A Clinical Study to Evaluate the Safety and Efficacy of RGB-5088 in Patients With Type 2 Diabetes Mellitus

Inclusion Criteria: * Age 18-65 years (inclusive), male or female. * Diagnosis of type 2 diabetes mellitus (T2DM) with a disease duration ≥5 years. * Body mass index (BMI) 18-30 kg/m². * Glycated hemoglobin (HbA1c) 7.0%-10.0%. * Adherence to guideline-recommended diet and exercise control; willing and able to comply with lifestyle interventions throughout the study. * On insulin therapy following adequate trials of standard and advanced glucose-lowering regimens as per guidelines. * Subjects are dependent on insulin therapy. * Women of childbearing potential, or male participants whose partners are of childbearing potential, must agree to use highly effective contraception throughout the study and for at least 6 months post-treatment. * Able to understand the study protocol, willing to participate voluntarily, and provide signed written informed consent. Exclusion Criteria: * Diagnosis of any form of diabetes other than T2DM. * Daily insulin dose \>1.5 U/kg or total daily dose \<20 U. * Fasting plasma glucose ≥15.0 mmol/L. * Positive for any diabetes-related autoantibodies at screening (prior to adipose tissue collection). * Proliferative diabetic retinopathy requiring treatment or unstable. * Active infection; hepatitis B, hepatitis C, syphilis, HIV antibody positivity; or history of tuberculosis. * History of major cardiovascular or cerebrovascular disease. * Uncontrolled hypertension despite pharmacological therapy. * Clinically significant abnormal liver function tests. * Clinically significant abnormal renal function tests. * Clinically significant abnormalities in hematology parameters. * Positive pregnancy test; breastfeeding. * History of malignant tumor, except for malignancies with an excellent expected prognosis after curative treatment. * History of tobacco dependence, alcohol abuse, substance abuse, or illicit drug use. * Use of concomitant medications (other than current antidiabetic agents) that, in the Investigator's opinion, may interfere with glycemic control. * Any active autoimmune disease or history of autoimmune disease deemed by the Investigator to be incompatible with study participation. * Documented history of a psychiatric disorder. * History of hemoglobinopathy, other significant hematological disorders, or any condition causing hemolysis or erythrocyte instability. * Participation in another interventional clinical trial within 3 months prior to signing the Informed Consent Form. * Prior islet cell infusion/transplantation. * Receipt of any other stem cell therapy. * Judged by the Investigator to have poor compliance or unwillingness to adhere to study procedures.