The purpose of this study is to evaluate the efficacy and safety of investigational doses of once weekly dulaglutide when added to metformin in participants with type 2 diabetes with inadequate blood sugar control.

Inclusion Criteria:

• Have type 2 diabetes mellitus (T2DM) for at least 6 months
• Have been treated with stable metformin dose for at least 3 months
• Have HbA1c ≥7.5% and ≤11.0% at study entry
• Have body mass index (BMI) ≥25 kilograms per meter squared (kg/m^2)

Exclusion Criteria:

• Have type 1 diabetes mellitus
• Have used any glucagon-like peptide-1 receptor agonist (GLP-1 RA) or insulin, not including prior short term insulin use (≤14 days)
• Have been taking any other medicine for diabetes (other than metformin) during the last 3 months
• Have used in the last 3 months (or plan to use) prescription weight loss medications
• Have disorders associated with slowed emptying of the stomach contents, or have had any stomach surgeries for the purpose of weight loss
• Current participation in or intent to begin during the study an organized diet and/or exercise weight reduction program (other than the lifestyle and dietary measures for diabetes)
• Have acute or chronic hepatitis, signs and symptoms of any other liver disease other than nonalcoholic fatty liver disease (NAFLD), or alanine transaminase (ALT) level >2.5 times the upper limit of the reference range, as determined by the central laboratory at study entry; participants with NAFLD are eligible for participation in this trial
• Had chronic or acute pancreatitis any time prior to study entry
• Have had a heart attack or stroke in the past 2 months, or have heart failure that significantly limits their physical activity
• Estimated glomerular filtration rate (eGFR) <30 milliliters/minute/1.73m^2 (or lower than the country-specific threshold for discontinuing metformin therapy per local label), calculated by the Chronic Kidney Disease-Epidemiology (CKD-EPI) equation, as determined by the central laboratory at study entry and confirmed at lead-in
• Have a personal or family history of medullary thyroid carcinoma or personal history of multiple endocrine neoplasia syndrome type 2
• Have proliferative retinopathy or maculopathy requiring acute treatment according to the opinion of the investigator

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 and 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.