Inclusion Criteria:
1. Male or female participants aged 18 to 65 years, inclusive, at the time of informed consent.
2. Type 2 diabetes mellitus diagnosed at least 3 months before screening according to the Chinese Guidelines for the Prevention and Treatment of Diabetes (2024 edition), and meeting one of the following: (a) management with diet and exercise alone for at least 3 months before screening; or (b) oral metformin at a stable dose of ≥1500 mg/day or a maximum tolerated dose of ≥1000 mg/day, alone or with an SGLT2 inhibitor at a stable dose, for at least 8 weeks before screening.
3. HbA1c of 7.5% to 10.5%, inclusive, at screening, as measured by the local laboratory.
4. Body weight ≥50 kg and body mass index of 19 to 35 kg/m², inclusive.
5. Self-reported or documented body weight change of no more than 5% within the 3 months before screening.
6. Willing and able to maintain a stable residence, remain contactable, and maintain a regular daily routine and diet and exercise management throughout the study.
7. Fully understands the study procedures, can communicate effectively with the investigator, understands and can comply with study requirements, and is willing to sign the informed consent form.
Exclusion Criteria:
1. Previous diagnosis or suspicion of type 1 diabetes, other specific types of diabetes, or secondary diabetes.
2. Acute complications of diabetes within 6 months before screening, including diabetic ketoacidosis, lactic acidosis, or hyperosmolar hyperglycemic state.
3. A Level 3 hypoglycemic event or at least three hypoglycemic events within 6 months before screening.
4. History or current presence of proliferative retinopathy or maculopathy, painful diabetic neuropathy, diabetic foot ulceration, or intermittent claudication.
5. A hematologic disorder or other condition at screening that may affect HbA1c measurement, including known hemoglobinopathy, hemolytic anemia, sickle cell anemia, blood transfusion within 3 months before screening, or severe blood loss within that period.
6. Any of the following local laboratory or 12-lead electrocardiogram findings during screening:
* Fasting plasma glucose \>11.1 mmol/L.
* Thyroid-stimulating hormone \>6.0 mIU/L or \<0.4 mIU/L.
* Alanine aminotransferase or aspartate aminotransferase ≥2 times the upper limit of normal (ULN), or total bilirubin ≥2 × ULN.
* Fasting triglycerides \>5.65 mmol/L.
* Serum amylase or lipase ≥1.5 × ULN.
* Estimated glomerular filtration rate \<60 mL/min/1.73 m².
* Calcitonin ≥50 ng/L.
* Hemoglobin \<110 g/L in males or \<100 g/L in females.
* Electrocardiographic heart rate \<55 or \>110 beats/minute.
* Second- or third-degree atrioventricular block, long QT syndrome, QTcF \>450 ms in males or \>470 ms in females, left bundle branch block, complete right bundle branch block, pre-excitation syndrome, or other clinically significant arrhythmia, except asymptomatic sinus arrhythmia.
7. Systolic blood pressure ≥160 mmHg or diastolic blood pressure ≥100 mmHg at screening.
8. Personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2.
9. History or current presence of severe gastrointestinal disease or relevant surgery, including acute or chronic pancreatitis, hepatitis, cholecystitis (except after cholecystectomy), or intestinal obstruction.
10. Heart failure of New York Heart Association Class III or IV, unstable angina, stroke, myocardial infarction, or coronary revascularization within 6 months before screening; or planned coronary, carotid, or peripheral arterial revascularization at screening.
11. Acute infection within 2 weeks before screening.
12. Any malignancy within the previous 5 years or currently, except cured basal cell carcinoma of the skin or cervical carcinoma in situ.
13. History or current presence of a condition that may require repeated or long-term systemic glucocorticoid therapy, such as systemic lupus erythematosus, inflammatory bowel disease, or asthma. Topical, intraocular, and intranasal glucocorticoids are excluded from this restriction.
14. Known or suspected allergy to VCT220 tablets, glucagon-like peptide-1 receptor agonists (GLP-1 RAs), or excipients.
15. Previous discontinuation of a GLP-1 RA because of safety or tolerability concerns.
16. Insulin treatment within 3 months before screening, or treatment with any glucose-lowering medication other than metformin or an SGLT2 inhibitor during that period, including traditional Chinese medicines used to lower blood glucose.
17. Positive hepatitis B surface antigen at screening, except when quantitative hepatitis B virus DNA is below the lower limit of the assay reference range and the participant is not receiving anti-hepatitis B medication at screening; or positive hepatitis C virus antibody, human immunodeficiency virus antibody, or syphilis antibody.
18. Significantly active or unstable major depressive disorder or another severe psychiatric disorder within 2 years before screening, or any history of attempted suicide.
19. History of alcohol or drug abuse within 3 months before screening. Alcohol abuse is defined as more than 7 units per week; one unit is 360 mL of beer containing 5% alcohol, 45 mL of spirits containing 40% alcohol, or 150 mL of wine containing 12% alcohol.
20. Treatment with any other investigational product within 3 months or 5 half-lives before screening, whichever is longer, or plans to participate in another clinical trial during this study.
21. Pregnancy or breastfeeding; a male or female participant of reproductive potential unwilling to use highly effective contraception throughout the study and for 3 months after the last dose; plans to conceive or donate sperm or oocytes during that period; or a positive pregnancy test during screening.
22. An employee of the sponsor, a study site, or the contract research organization, or an immediate family member of such an employee.
23. Considered unsuitable for study participation by the study site.
