Study to Evaluate HM15275 in Subjects With Type 2 Diabetes Mellitus

Key Inclusion Criteria 1. Participant's age at the time of signing the informed consent: * United States: 18 to 75 years (inclusive) 2. Diagnosed with type 2 diabetes mellitus (T2DM) with HbA1c ≥7.0% and ≤10.0% at screening 3. Treated with diet and exercise alone or on a stable dose of metformin (≥1000 mg/day) for at least 3 months prior to screening 4. BMI ≥25 kg/m² and ≤50 kg/m² 5. Body weight change \<5% over the past 3 months prior to screening 6. Capable of giving signed informed consent and willing to comply with all protocol procedures Key Exclusion Criteria 1. Type 1 diabetes mellitus or use of glucose-lowering medications other than metformin within 3 months prior to screening 2. Poor glycemic control (fasting plasma glucose \>270 mg/dL) 3. History of diabetic ketoacidosis or severe hypoglycemia within 6 months 4. Clinically significant cardiovascular disease (e.g., NYHA class III/IV heart failure, recent myocardial infarction, stroke, or revascularization within 3 months) 5. History of pancreatitis or factors increasing the risk of pancreatitis 6. Personal or family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia type 2 7. Clinically significant liver disease, renal impairment (eGFR \<60 mL/min/1.73 m²), or abnormal laboratory findings at screening 8. Participation in another investigational study within 30 days or within 5 half-lives of the investigational product, whichever is longer; for GLP-1 receptor agonist-related or weight loss studies, participation within 3 months prior to screening