A Phase II, Randomized, Double-Blind, Placebo-Controlled, Dose-Ranging, Two-Staged, Fixed Design Study to Evaluate the Efficacy, Safety, Tolerability and Pharmacokinetics of P2202 in Overweight/Obese Patients of Type 2 Diabetes Mellitus Inadequately Controlled on Metformin, Sulphonylurea, or Both.