A Study of Tirzepatide (LY3298176) Compared With Placebo in Adults With Type 1 Diabetes and Obesity or Overweight

Inclusion Criteria: * Have type 1 diabetes and on insulin treatment for at least one year prior to screening * Have an HbA1c value of 7.0% to 10.5% inclusive, at screening * Have a body mass index (BMI) of ≥25 kilograms per square meter (kg/m2) at screening * Are of stable weight for at least 90 days prior to screening and agree to not start an intensive diet or exercise program during the study Exclusion Criteria: * Have experienced two or more events requiring hospitalization due to poor glucose control (hyperglycemia or (diabetic ketoacidosis (DKA)) during the period of 180 days prior to screening and until randomization. * Have experienced one or more events of severe hypoglycemia during the period of 90 days prior to screening and until randomization. * Are currently receiving or planning to receive treatment for diabetic retinopathy and/or macular edema * Have had chronic or acute pancreatitis * Have used any weight loss drugs or alternative remedies, including herbal or nutritional supplements, within 90 days prior to screening