A Study for Patients With Type 1 Diabetes

Comparison of blood glucose levels in patients with Type 1 diabetes when they take a new basal insulin analog and when they take insulin glargine

Prestudy treatment for patients who enter this study will be once daily insulin glargine along with mealtime insulins. Patients will continue to use their mealtime insulins throughout the study. The study will consist of 16 weeks of treatment and 4 weeks of follow-up. The 16 weeks of treatment will consist of two 8-week periods (Periods 1 and 2) during which patients will receive insulin glargine for 8 weeks and LY2605541 for 8 weeks in a random sequence. During the 4-week follow-up period, patients will return to insulin glargine or another basal insulin recommended by the investigator.

Eligibility Criteria:
Inclusion Criteria:

* Type 1 diabetes mellitus (T1DM) for at least 1 year and using insulin glargine for at least 6 months with a maximum daily dose of 1 unit per kilogram (U/kg).
* Hemoglobin A1c (HbA1c) of no greater than 10.5% before randomization
* Body mass index (BMI) 19 to 45 kilogram per square meter (kg/m²)
* Capable and willing to prepare and inject insulin with a syringe, monitor own blood glucose, complete the study diary, be receptive to diabetes education, comply with study requirements, and receive telephone calls during treatment
* Women of childbearing potential must test negative for pregnancy before receiving treatment and agree to use reliable birth control until completing the follow-up

Exclusion Criteria:

* Twice daily use of insulin glargine within 30 days prior to the study
* Use of any oral or injectable medication intended for the treatment of diabetes mellitus other than insulins in the 3 months prior to the study
* Use of an insulin pump
* More than 1 episode of severe hypoglycemia within 3 months prior to the study, or currently diagnosed as having hypoglycemia unawareness
* 2 or more emergency room visits or hospitalizations due to poor glucose control in the 6 months preceding the study
* Known hypersensitivity or allergy to any of the study insulins or their excipients
* Blood transfusion or severe blood loss within 3 months prior to the study or known hemoglobinopathy, hemolytic anemia, or sickle cell anemia, or any other traits of hemoglobin abnormalities known to interfere with the HbA1c methodology
* Irregular sleep/wake cycle
* Pregnant or intend to become pregnant during the study
* Women who are breastfeeding
* Use of prescription or over-the-counter medications to promote weight loss within 3 months prior to the study
* Current participation in a weight loss program or plans to do so during the study
* Use of chronic (lasting longer than 14 consecutive days) systemic glucocorticoid therapy currently or within 4 weeks prior to the study
* Cardiac disease with a marked impact on physical functioning
* Clinically significant electrocardiogram (ECG) abnormalities at screening
* Fasting triglycerides greater than 500 milligram per deciliter (mg/dL)
* Liver disease
* History of renal transplantation, current renal dialysis, or creatinine greater than 2.0 mg/dL (177 micromole per liter \[μmol/L\])
* Malignancy other than basal cell or squamous cell skin cancer, currently or within the last 5 years
* Treatment with any antibody-based therapy within 6 months prior to the study