The main purpose of this study is to learn about the side effects of LY3502970 when given to Japanese participants with type 2 diabetes mellitus (T2DM). Blood tests will be performed to investigate how the body processes the study drug and how the study drug affects the body. For each participant, the study will last up to 24 weeks, inclusive of screening and will include 10 visits to the study center.

Inclusion Criteria:

• Males and females not of childbearing potential
• Have type 2 diabetes mellitus (T2DM) diagnosed for at least 1 year
• Have glycated hemoglobin (HbA1c) value ≥ 7.0% and ≤ 10.0% for participants treated with diet and exercise or HbA1c ≥ 6.5% and ≤ 9.0% for participants who have washed out antidiabetic medications at screening
• Have type 2 diabetes controlled with diet and exercise alone or are stable on a single oral antidiabetic medication (OAM); either metformin, DPP-4 (dipeptidyl peptidase-4) inhibitor, or SGLT2 (sodium-glucose co-transporter-2) inhibitor within 3 months prior to screening. Participants must withdraw from their OAM treatment for at least 28 days prior to dosing.

Exclusion Criteria:

• Have type 1 diabetes mellitus or latent autoimmune diabetes in adults.
• Have uncontrolled diabetes defined as an episode of ketoacidosis or hyperosmolar state requiring hospitalization
• Have had an episode of severe hypoglycemia, as defined by the occurrence of neuroglycopenic symptoms requiring the assistance of another person for recovery or have a history of hypoglycemia unawareness or poor recognition of hypoglycemic symptoms.
• Have a history of acute or chronic pancreatitis or fasting serum triglyceride level of >500 milligram per deciliter (mg/dL).
• Have known liver disease, obvious clinical signs or symptoms of liver disease, acute or chronic hepatitis, or have elevations in aminotransferases (alanine aminotransferase [ALT] and aspartate aminotransferase [AST]) greater than 3× upper limit of normal (ULN).