The main purpose of this study is to investigate the safety and tolerability of the study drug LY3457263 when administered alone or in combination with glucagon-like peptide 1 (GLP-1) receptor agonist (RA) in participants with type 2 diabetes. Blood tests will be performed to investigate how the body processes the study drug and how the study drug affects the body. The study will last up to approximately 16 weeks excluding the screening period for each participant and include up to 17 visits.

Inclusion Criteria:

• Participants with type 2 diabetes (T2D) at least 6 months before screening
• Participants treated for T2D with diet and exercise, with or without metformin
• Have a glycated hemoglobin A1c (HbA1c) value of ≥ 7.5% and ≤10.5%
• Have had a stable body weight for 3 months and body mass index (BMI) of 27.0 to 45.0 kilograms per meter squared (kg/m²)
• Male participants who agree to use effective methods of contraception and female participants not of childbearing potential

Exclusion Criteria:

• Have a history of or current cardiovascular, respiratory, hepatic, renal, GI, endocrine (apart from T2D), hematological, or neurological disorders capable of altering the absorption, metabolism, or elimination of drugs
• Have type 1 diabetes mellitus or latent autoimmune diabetes in adults or maturity-onset diabetes of the young
• Have a history of proliferative diabetic retinopathy, diabetic maculopathy, or severe non-proliferative diabetic retinopathy
• Have known allergies to GLP-1 receptor agonists