The study is being conducted to evaluate the efficacy and safety of HRS9531 compared with placebo in participants with type 2 diabetes mellitus not adequately controlled with basal insulin, with or without metformin and/or sodium-glucose cotransporter-2 (SGLT2) inhibitor. The study may include up to 23 visits.

Inclusion Criteria:

1. Male or female, able and willing to provide a written informed consent
2. Diagnosed with type 2 diabetes ≥ 90 days；
3. On stable once-daily dose of basal insulin alone or in combination with metformin and/or SGLT2 inhibitor ≥ 90 days;
4. HbA1c was 7.5%~11.0% (both inclusive);
5. Body Mass Index (BMI) ≥22 kg/m2 at screening.

Exclusion Criteria:

1. A history of type 1 diabetes, specific diabetes, or secondary diabetes;
2. Have a history of severe hypoglycemia within t180 days prior to screening;
3. History of acute cardiovascular and cerebrovascular diseases within 180 days prior to screening；
4. Have a history of malignancy within 5 years;
5. Known or suspected allergy or intolerance to the investigational medicinal products or related products;
6. Participation in any clinical trial of an approved or non-approved investigational product/treatment within the last 90 days;
7. Any conditions that the Investigator judges might not be suitable to participate in the trial.