Insulin Lispro 6 Days Versus Insulin Aspart 6 Days in Pump Use

Inclusion Criteria: * Diagnosed with type 1 diabetes (World Health Organization criteria) for at least 24 months * Treated with continuous subcutaneous insulin infusion (CSII) therapy for the previous 6 months * Mean total daily insulin dose for 3 days prior to screening less than or equal to 46 units/day if using a 300-Unit reservoir, less than or equal to 30 units/day if using a 200 unit reservoir, or less than or equal to 26 units/day if using a 180 unit reservoir * Baseline body mass index (BMI) less than or equal to 35.0 kilograms per meter squared (kg/m2) * Baseline glycated hemoglobin A1c (HbA1c) 5% to 9% Exclusion Criteria: * Impaired renal function (serum creatinine greater than or equal to 2.0 milligrams per deciliter (mg/dL)) * Legal blindness * Have had any episode in the 12 months prior to screening of hypoglycemic coma, seizures, or disorientation * Have had hypoglycemia unawareness (routinely asymptomatic at blood glucose less than 45 mg/dL \[2.5 millimoles per liter (mmol/L)\]) in the 12 months prior to screening. * Have had any emergency room visits or hospitalizations due to poor glucose control in the 12 months prior to screening. * Have had a pump-related infusion site abscess in the 12 months prior to screening. * Have had multiple, clinically significant occlusions as judged by the investigator. * Have had any infection with Staphylococcus aureus in the past 5 years * Have one of the following concomitant diseases: presence of clinically significant hematologic, oncologic, renal, cardiac, hepatic, or gastrointestinal disease, or any other serious disease considered by the investigator to be exclusionary. * Participants with malignancy other than basal cell or squamous cell skin cancer who have not yet been treated, are currently being treated, or who were diagnosed less than 5 years ago. * Have had a blood transfusion or severe blood loss within the 3 months prior to screening or have known hemoglobinopathy, hemolytic or sickle cell anemia, or any other traits of hemoglobin abnormalities known to interfere with HbA1c methodology. * Are receiving chronic systemic glucocorticoid therapy, or have received such therapy within the 4 weeks preceding screening. * Have an irregular sleep/wake cycle in the investigator's opinion. * Have a known hypersensitivity or allergy to any of the study insulins or their excipients * Are breastfeeding or pregnant, or intend to become pregnant during the course of the study, or are sexually active women of childbearing potential not actively practicing birth control by a method determined by the investigator to be medically acceptable. * Are currently enrolled in, or discontinued within the last 30 days from a clinical trial involving off-label use of an investigational drug or device, or currently enrolled in any other type of medical research not to be scientifically or medically compatible with this study. * Are unwilling or unable to comply with the use of a data collection device to directly record data from the participant.