The purpose of this study is to investigate the efficacy and safety of retatrutide compared with semaglutide in participants with Type 2 Diabetes and inadequate glycemic control with metformin with or without sodium-glucose cotransporter-2 inhibitor (SGLT2i). The study will last about 26 months and may include up to 24 visits.

Inclusion Criteria:

• Have Type 2 Diabetes (T2D)
• Have HbA1c ≥ 7.0% (53 millimoles per mole (mmol/mol)) to ≤ 10.5% (91 mmol/mol)
• Have been on a stable diabetes treatment consisting of metformin ≥ 1500 milligrams per day (mg/day) with or without SGLT2i during 90 days prior to screening
• Are of stable weight for at least 90 days prior to screening
• Have a Body Mass Index (BMI) ≥ 25.0 kilograms per meter squared (kg/m^2)

Exclusion Criteria:

• Have Type 1 Diabetes (T1D)
• Have a history of ketoacidosis or hyperosmolar state or coma within the last 6 months prior to screening
• Have a history of severe hypoglycemia or hypoglycemia unawareness within the last 6 months prior to screening
• Are currently receiving or planning to receive treatment for diabetic retinopathy and/or macular edema
• Have an estimated glomerular filtration rate (eGFR) <45 milliliters/minute/1.73 meter squared (mL/min/1.73 m^2) or lower than the country-specific threshold for discontinuing metformin therapy per local label as determined by the central laboratory
• Have a prior or planned surgical treatment for obesity
• Have New York Heart Association Functional Classification IV congestive heart failure
• Have had an acute myocardial infarction, stroke, or were hospitalized for congestive heart failure within 90 days prior to screening
• Have a known clinically significant gastric emptying abnormality
• Have a history of an active or untreated malignancy or are in remission from a clinically significant malignancy for less than 5 years
• Have any lifetime history of a suicide attempt
• Had chronic or acute pancreatitis
• Have a family or personal history of medullary thyroid carcinoma or multiple endocrine neoplasia (MEN) syndrome Type 2
• Have taken prescribed or over-the-counter medication, or alternative remedies, intended to promote body weight reduction within 90 days prior to screening.

Anonymized individual patient level data will be provided in a secure access environment upon approval of a research proposal and a signed data sharing agreement.

Data are available 6 months after the primary publication or approval of the indication studied in the US and EU, whichever is later. Data will be indefinitely available for requesting.

A research proposal must be approved by an independent review panel and researchers must sign a data sharing agreement.