Pharmacodynamic Effects of Lixisenatide Compared to Liraglutide in Patients With Type 2 Diabetes Not Adequately Controlled With Insulin Glargine With or Without Metformin

Primary Objective: - To investigate the effects of repeated subcutaneous doses of lixisenatide 20 μg once daily (QD) as compared to liraglutide 1.2 mg QD or 1.8 mg QD in reducing post-prandial plasma glucose (PPG) assessed as area under the plasma glucose-concentration-time curve (AUC) after a standardized breakfast at the end of a 8-week treatment period in participants with type 2 diabetes mellitus (T2DM) not adequately controlled with insulin glargine (± metformin). Secondary Objectives: * To assess the effects of lixisenatide 20 μg QD as compared to liraglutide 1.2 QD or 1.8 mg QD after an 8-week treatment period in participants with T2DM not adequately controlled with insulin glargine (± metformin) on: * Post-prandial C-peptide, glucagon and appetite perceptions after a standardized breakfast, * Appetite perceptions after standardized dinner, * Gastric emptying after a standardized labelled test meal, * Fasting plasma glucose, 24-hour plasma glucose profile, * Glycosylated hemoglobin (HbA1c), * Insulin glargine dose, * 7-point self monitored plasma glucose (SMPG), * Body weight and waist circumference, * 24-hour heart rate and blood pressure, * To assess lixisenatide and liraglutide safety and tolerability as add on treatment to insulin glargine (± metformin).