Insulin Glargine (Lantus) vs Sulfonylurea (SU) for BETA Cell Function (BETA Study)

List of Inclusion and Exclusion Criteria: Inclusion Criteria: * Type 2 Diabetes Mellitus patients on metformin monotherapy * 7% ≤ HbA1c ≤ 12% * 20 kg/m² ≤BMI ≤ 35 kg/m² * Diabetes duration: at least 6 months Exclusion Criteria: * Type 1 Diabetes Mellitus patients * Clinical evidence of active liver disease, or serum Alanine AminoTransferase 3 times the upper limit of the normal range * Serum creatinine: 1.5 mg/dl for males, 1.4 mg/dl for females * Acute and chronic metabolic acidosis, including diabetic ketoacidosis * History of alcohol or other substance abuse * Pregnancy or not using contraceptive in childbearing aged women * Known hypersensitivity to Lantus, SU or metformin * Any disease or condition that in the opinion of the investigator may interfere with completion of the study The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.