Primary objective: To demonstrate the superiority of insulin glargine over liraglutide in terms of percentage of patients reaching a Glycosylated Haemoglobin (HbA1c) \< 7% at the end of the comparative period (24 weeks) in Type 2 diabetic patients failing lifestyle management and oral agents Secondary objectives of the comparative period (24 weeks): \>To assess the effect of insulin glargine in comparison with liraglutide on: * HbA1c level * Percentage of patients whose HbA1c has decreased but remains \>= 7% at the end of the comparative period * Percentage of patients whose HbA1c has increased at the end of the comparative period * Fasting Plasma Glucose (FPG) * 7-point Plasma Glucose (PG) profiles * Hypoglycemia occurrence * Body weight * Adverse events Objectives of the extension period (24 weeks): \>To assess the effect of insulin glargine in patients not adequately controlled with liraglutide on: * HbA1c level * FPG * 7-point PG profiles * Hypoglycemia occurrence * Body weight * Adverse events

Maximum estimated study duration per patient: either 27 weeks (patients randomized to insulin glargine arm) or 51 weeks (patients randomized to liraglutide arm) broken down as follow: * A 2-week of screening period, * A 24-week comparative period, * A 24-week extension period (only for patients treated with liraglutide, not adequately controlled at the end of the comparative period), * A 1-week follow-up period