The purpose of this study is to is to evaluate the efficacy and safety of retatrutide in participants with type 2 diabetes in participants who have obesity or overweight (J1I-MC-GZBK master protocol) including a subset of participants who have obstructive sleep apnea (OSA) (J1I-MC-GSA2). The study will last about 89 weeks and will include up to 24 visits.

Inclusion Criteria:

• Have a body mass index (BMI) greater than or equal to 27.0 kilogram/square meter (kg/m ²)
• Have Type 2 Diabetes (T2D)
• Are on stable treatment for T2D for at least 90 days
• Have a history of at least one unsuccessful dietary effort to lose body weight.

GSA2 Inclusion Criteria

• Previously diagnosed with OSA
• Have AHI ≥15 on polysomnography at screening (definition of moderate-to-severe OSA)
• For participants not on positive airway pressure (PAP) therapy: unable or unwilling to use PAP therapy and have not used PAP for at least 4 weeks prior to screening.
• If on PAP therapy, have been on PAP therapy for at least 3 consecutive months prior to screening, and willing to temporarily stop using PAP therapy for approximately 7 days prior to each of the sleep study (PSG) visits.

Exclusion Criteria:

• Have a self-reported or documented change in body weight >5 kg (11 pounds) within 90 days.
• Have taken weight loss drugs, including over-the-counter medications, within 90 days prior to screening.
• Have a prior or planned surgical treatment for obesity.
• Have Type 1 diabetes
• Have a family or personal history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2 (MEN-2)
• Have had pancreatitis

GSA2 Exclusion Criteria

• Use stimulants (for example, modafinil, armodafinil, solriamfetol, pitolisant, amphetamine) less than 3 months prior to screening.
• Use hypnotics, mirtazapine, opioids, trazodone, and zonisamide less than 3 months prior to screening.
• Use a dental appliance or other device to treat OSA other than PAP therapy.

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

a are available 6 months after the primary publication and approval of the indication studied in the US and European Union (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.