['diabetes mellitus, type 2']
['ttp399 400 mg', 'ttp399 800 mg', 'sitagliptin 100 mg', 'placebo']

        Inclusion Criteria:

          -  A historical diagnosis of Type 2 Diabetes in accordance with the American Diabetes
             Association (ADA) guidelines, with diagnosis at least 6 months prior to Screening.

          -  On a stable (for the last 3 months prior to screening) regimen of metformin
             monotherapy equivalent of at least 1000 mg once daily.

          -  Males, females of childbearing potential (must have a negative pregnancy test and be
             willing to comply with protocol contraception), and females of non-childbearing
             potential.

          -  Age 18 to 75 years, inclusive, at the time of screening.

          -  HbA1c ≥7.0% and ≤9.5%.

          -  Generally stable health without active infection or history of major surgery or
             significant injuries within the last year.

        Exclusion Criteria:

          -  Diagnosis of Type 1 diabetes mellitus, maturity-onset diabetes of the young,
             insulin-requiring Type 2 Diabetes, other unusual or rare forms of diabetes mellitus,
             or history of diabetic ketoacidosis.

          -  Clinically significant abnormal lab values including eGFR <50ml/min/1.73m2, ALT,
             bilirubin or AST >1.5 X ULN, hypokalemia or other clinically significant electrolyte
             abnormality.

          -  History of myocardial infarction, unstable angina, coronary revascularization, stroke,
             or transient ischemic attack within 2 years of screening.

          -  Presence of symptomatic congestive heart failure.

          -  History of cardiac arrhythmias requiring treatment or prophylaxis with drugs or
             devices during the last 2 years or any history of atrial fibrillation or flutter
             beyond a single short-term episode (e.g., lasting 1-2 days).

          -  History or presence of a 2nd degree or greater atrioventricular block in the absence
             of a pacemaker.

          -  A 12-lead ECG, from screening or baseline demonstrating QTcF interval >450 msec for
             males or >47 msec for females.

          -  A family or personal history of long QT syndrome.

          -  History of pancreatitis.

          -  Persistent, uncontrolled hypertension.

          -  Presence of chronic active hepatitis (hepatitis B, hepatitis C, nonalcoholic
             steatohepatitis [NASH]) and/or known liver cirrhosis.

          -  Participation in any formal weight loss program, or fluctuation of > 5% in body
             weight, or having received medications approved for weight loss within 3 months prior
             to screening.

          -  A positive pre-study drug screen.

          -  Participation in a clinical trial and receipt of an investigational product within 30
             days.

          -  Have a history of drug abuse within 2 years of screening or a positive pre-screen drug
             screen.

          -  Have a history of hypoglycemic episode requiring glucose, glucagon, or orange juice
             administered by someone other than the patient within 6 months prior to screening.

          -  A history of excessive alcohol consumption within the last 2 years prior to screening

          -  Mental or legal incapacitation.

          -  Blood donation of approximately 1 pint (500 mL) within 8 weeks.

          -  History of MEN-2 or family history of medullary thyroid cancer.

          -  History of cancer, other than non-melanoma skin cancer, that required therapy in the 5
             years prior study start.
      