This trial is to evaluate the efficacy and safety of CWP-0403 compared to Sitagliptin by proving non-inferiority in patients with type 2 Diabetes Mellitus insufficiently controlled with metformin alone.

Inclusion Criteria:

• Patients who had diagnosed with type 2 DM before 3 months
• Men and women between the age of ≥ 19 and ≤ 75 years
• FPG ≤ 270 mg/dL at screening visit
• Patients who consent to participate in this trial by written Informed Consent Form

Exclusion Criteria:

• Type 1 DM or secondary diabetes
• Subjects who are administrating oral anti-hyperglycemic drugs or have to take a medicine
• Body mass index < 20 kg/m2 or > 40.0kg/m2
• Subjects who are assessed to be inappropriate for this trial by investigator