The aim of this trial is to investigate the safety, tolerability, pharmacokinetics, and efficacy of THDBH120 injection in participants with T2DM. This study includes three multiple-ascending dose cohorts.

Inclusion Criteria:

• Male or female patients 18 to 75 years of age, inclusive;
• Have T2DM for at least 6 months before screening based on the disease diagnostic criteria (World Health Organization [WHO] Classification for Diabetes);
• Treated with diet and exercise alone, or a stable dose of metformin (≥1000 mg/day and not more than the locally approved dose) for at least 2 months prior to screening;
• Have a BMI between 23 and 35 kg/m²(inclusive) at screening;
• HbA1c levels: 7.0% to 10.0% (inclusive) for subjects treated by diet or exercise alone; 7.0% to 9.0% (inclusive) for subjects receiving stable-dose metformin.

Exclusion Criteria:

• Have been diagnosed with proliferative diabetic retinopathy, diabetic maculopathy, or non-proliferative diabetic retinopathy requiring treatment during the study;
• Have a personal or family history of medullary thyroid carcinoma or have multiple endocrine neoplasia type 2;
• Have diagnosed hyperthyroidism or hypothyroidism;
• Have grade 2 hypoglycemia events or grade 3 hypoglycemia events within 6 months prior to screening;
• Have a history of ketoacidosis, lactic acidosis, or hyperosmolar state leading to hospitalization within 6 months prior to screening;
• Presence of uncontrolled hypertension at screening: systolic blood pressure ≥160 mmHg and/or diastolic blood pressure ≥100 mmHg;
• Prolonged QTcF interval on 12-lead ECG at screening (QTcF≥450 ms for males, >470 ms for females), PR interval >200 ms, or the presence of long QT syndrome, second- or third-degree atrioventricular block, left or right bundle branch block, Wolff-Parkinson-White syndrome, or any other clinically significant arrhythmias (except sinus arrhythmia);
• Weight change ≥ 5% within 3 months prior to screening;
• Have been treated with insulin, excluding insulin therapy for gestational diabetes mellitus, or acute/temporary insulin therapy (≤ 14 days) for conditions such as acute illness, hospitalization, or elective surgery.