A Study on Safety and Tolerability of SAR425899 in Overweight to Obese Subjects and Type 2 Diabetes Mellitus Patients Not Requiring Anti-Diabetic Pharmacotherapy With an Optional 6-month Safety Extension Period

Primary Objectives: * Main study: To assess in overweight to obese subjects and type 2 diabetes mellitus (T2DM) patients not requiring anti-diabetic pharmacotherapy the safety and tolerability of 3 different dose escalation regimens of SAR425899 in terms of the relative and absolute frequency and severity of gastrointestinal (GI) adverse events (AEs). * Six-month safety extension period: To assess the safety and tolerability of SAR425899 after 6 months treatment at the maximum dose that was individually well tolerated during the main part of the study in terms of the relative and absolute frequency and severity of GI AEs. Secondary Objectives: Main study and 6-month study extension period: To assess in overweight to obese subjects and T2DM patients not requiring anti-diabetic pharmacotherapy: * The effect of once-daily dosing of SAR425899 on body weight (BW), fasting plasma glucose (FPG), and hemoglobin A1c (HbA1c). * Safety and tolerability.

Main study: The maximum study duration is approximately 12 weeks per patient (up-to 3-week screening period, 8-week treatment period, 3-day post treatment follow-up period). Six-month study extension period: The maximum study duration is approximately 9 months (up-to 3-week screening period, 8-month treatment period, 3-day post treatment follow-up period).