Safety/Efficacy Study of Subcutaneously Injected Prandial Insulins Compared to Insulin Lispro Alone in Participants With Type 1 Diabetes Mellitus

Criteria for randomization into the study included 1) fasting blood glucose and predinner
glucose values in the range of 70 to 140 milligrams per deciliter (mg/dL) approximately 60%
of the time for 7 days prior to randomization 2) 90 minute or 2-hour postprandial blood
glucose <220 mg/dL approximately 70% of the time for 7 days prior to randomization and 3)
successfully completed 3 days of 10-point glucose monitoring and have at least 4
self-monitored blood glucose values on all non-10-point monitoring days. Participants that
did not meet 1 or more of these criteria during a 4- to 6-week Titration Period were not
randomized.

Inclusion Criteria:

- Males or females aged ≥18 years

- Type 1 Diabetes Mellitus (T1DM) treated with insulin for ≥12 months

- Body mass index (BMI) 18.0 to 40.0 kilograms per square meter (kg/m^2).

- Hemoglobin A1C (HbA1C) level 6.7% to 8.2%, inclusive

- Fasting C-peptide <0.6 nanograms per milliliter (ng/mL)

- Willingness to use twice daily (BID) insulin glargine as basal insulin for the
duration of the study

- Willingness to avoid use of an insulin infusion pump or unblinded continuous glucose
monitoring (CGM) during the study

Exclusion Criteria:

- Known or suspected allergy to any component of any of the study drugs

- Use of pramlintide within 30 days of Screening

- Use of drugs during the study or within 30 days of Screening (such as corticosteroids
or antimetabolites) that could interfere with the interpretation of study results or
are known to cause clinically relevant interference with insulin action, glucose
utilization, or recovery from hypoglycemia

- Recurrent severe hypoglycemia (more than 2 episodes over the last 6 months) or
hypoglycemic unawareness, as judged by the Investigator