A 6-Month, Multicenter, Randomized, Open-label, Parallel-group Study Comparing the Efficacy and Safety of a New Formulation of Insulin Glargine and Lantus® Injected in the Morning or Evening in Patients With Type 1 Diabetes Mellitus With a 6-month Safety Extension Period

Primary Objective:

- To compare the efficacy of a new formulation of insulin glargine and Lantus (overall,
regardless the injection time) in terms of change of HbA1c from baseline to endpoint
(scheduled Month 6) in participants with type 1 diabetes mellitus

Secondary Objective:

- To compare HOE901-U300 and Lantus when given in the morning or in the evening in terms
of:

- Change of HbA1c from baseline to endpoint (scheduled Month 6)

- Change from baseline to endpoint (Month 6) in fasting plasma glucose (FPG), plasma
glucose prior to injection of study drug, plasma glucose at 03:00 hours, mean plasma
glucose (8-point profiles), glucose variability, treatment satisfaction and health
related quality of life in participants with Type 1 Diabetes Mellitus (T1DM)

- Reaching target HbA1c values and controlled plasma glucose (all and reaching target
without hypoglycemia)

- Frequency of occurrence and diurnal distribution of hypoglycemia by category of
hypoglycemia (symptomatic, asymptomatic, nocturnal, severe, probable and relative)

- Safety and tolerability of HOE901-U300 including development of anti-insulin antibody
(AIAs) during the 12-month study period