The goal for this study is to evaluate the efficacy and safety of RAY1225 versus placebo in participants with type 2 diabetes not under control with diet and exercise alone.

Inclusion Criteria:

1. Have been diagnosed with type 2 diabetes mellitus (T2DM)
2. Having received only dietary and exercise therapy and never taken any antihyperglycemic medications before screening; OR Having taken no antihyperglycemic medications within the 12 weeks before screening and, prior to that, having received only oral antihyperglycemic drugs in a regimen of no more than two concomitant agents.
3. Have a body mass index (BMI) ≥20 kilograms per meter squared (kg/m²) at screening
4. Be of stable weight (±5%) for at least 12 weeks before screening

Exclusion Criteria:

1. Have type 1 diabetes mellitus
2. Presence of severe chronic diabetic complications at screening, including but not limited to: proliferative diabetic retinopathy, diabetic macular edema, and severe non-proliferative diabetic retinopathy requiring acute treatment;
3. History of diabetic ketoacidosis or hyperosmolar hyperglycemic state within 24 weeks prior to randomization;
4. Occurrence of a Grade 3 hypoglycemic event within 12 months prior to screening, or ≥3 Grade 2 hypoglycemic events (venous or capillary blood glucose <3.0 mmol/L) within 3 months prior to screening, or presence of hypoglycemia-related symptoms ;
5. History of severe trauma, severe infection, or surgery within 12 weeks prior to screening that may affect glycemic control;
6. Receipt of blood transfusion within 12 weeks prior to screening, or blood donation/loss ≥400 mL within 12 weeks prior to screening, or blood donation/loss ≥200 mL within 4 weeks prior to screening, or known hemoglobinopathy (such as thalassemia, hemolytic anemia, sickle cell anemia, etc.);
7. Any unstable or treatment-requiring endocrine disorders related to glycemic control other than type 2 diabetes mellitus (such as hyperthyroidism, acromegaly, Cushing's syndrome, etc.).