The aim of the trial is to investigate the efficacy and safety of HRS9531 tablets versus placebo in participants with type 2 diabetes mellitus who failed to achieve adequate glycemic control on lifestyle intervention alone or on a stable dose of metformin. This study will last 20 weeks.

Inclusion Criteria:

1. Male or female, aged 18 to 70 years on the day of signing the informed consent form;
2. Have a documented history of type 2 diabetes mellitus for at least 6 months at screening, diagnosed according to the criteria in Guidelines for the Prevention and Treatment of Type 2 Diabetes in China (2024 Edition);
3. HbA1c between 7.5% and 10.5% at screening;
4. Have received lifestyle intervention alone for at least 8 weeks, or stable metformin monotherapy for at least 8 weeks prior to screening. Stable treatment is defined as no change in daily drug dosage, with no planned modifications to the regimen during the entire trial period;
5. Fasting plasma glucose ≤ 15 mmol/L;
6. Body mass index (BMI) between 20.0 kg/m² and 40.0 kg/m² at screening;
7. Voluntarily sign the informed consent form before the trial, fully understand the trial content, procedures and potential adverse reactions, and be able and willing to comply with protocol requirements to complete the study;
8. Have no fertility plans from the signing of the informed consent form until 2 months after the last dose, and agree to use highly effective contraceptive measures as specified in the protocol.methods.

Exclusion Criteria:

1. Participants with relevant abnormal test results at screening.
2. Participants with clinically significant abnormal findings on electrocardiogram (ECG) that, in the investigator's opinion, may compromise subject safety.
3. Participants with poorly controlled blood pressure.
4. Participants diagnosed with or suspected of having type 1 diabetes, specific types of diabetes, or secondary diabetes.
5. Participants who experienced acute diabetic complications within 6 months prior to screening.
6. Participants who experienced severe hypoglycemic events or recurrent hypoglycemic events within 6 months prior to screening.
7. Participants with severe chronic diabetic complications at screening, or non-proliferative diabetic retinopathy requiring treatment during the trial.
8. Participants with a past or known history or family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2 (MEN2).
9. Participants with a past or known history of acute or chronic pancreatitis, pancreatic injury, acute cholecystitis, or symptomatic/treatment requiring gallbladder disease.
10. Participants with a past history of significant gastrointestinal diseases (such as severe diabetic gastroparesis, gastric outlet obstruction, inflammatory bowel disease, active ulcer, etc.), or who have undergone gastrointestinal surgery (excluding gastrointestinal polypectomy and appendectomy), or who are taking long-term medications that directly affect gastrointestinal motility.
11. Participants with a history of severe cardiovascular or cerebrovascular diseases within 6 months prior to screening.
12. Participants with known or suspected depression, bipolar disorder, suicidal ideation, schizophrenia, or other severe psychiatric disorders; or participants who are mentally incompetent, have language barriers, are unable to fully understand the trial protocol, or are unwilling to cooperate with study site staff.
13. Participants with a history of malignant tumor within 5 years prior to screening, except for cured localized cancers such as localized basal cell carcinoma of the skin, cervical carcinoma in situ, and prostate carcinoma in situ.
14. Female participants who are pregnant, breastfeeding, or planning to become pregnant during the trial.
15. Any other conditions that, in the investigator's judgment, render the subject unsuitable for participation in this clinical trial.