The objectives of this study is to determine the safety profiles, tolerability, pharmacokinetics and pharmacodynamics of HMS5552 following single ascending doses in healthy adult subjects.

This will be a randomized, double-blind and placebo-controlled safety study with single oral doses of HMS5552 given to healthy volunteers.

The primary objective is to characterize the safety profiles of HMS5552 following single ascending doses (SAD) in healthy adult subjects.

The secondary objectives include:

1. To assess the pharmacokinetic profiles of HMS5552 after single dosing
2. To assess the preliminary pharmacodynamic profiles of HMS5552

Each study subject will receive a single oral dose of HMS5552. During each dosing, eight subjects will be allocated to receive HMS5552 and two subjects will be allocated to receive placebo treatment.

Several doses of HMS5552 will be tested. Dose titration or reduction is determined for each cohort based on the safety and pharmacokinetic data obtained from the lower dose cohorts.

Inclusion Criteria:

• Female and male volunteers, 18 to 45 years of age
• BMI: 18 to 24 kg/m2
• Fasting plasma glucose: 3.9 to 6.1 mmol/L
• Glucose level at 2 hours following oral glucose tolerance test <7.8 mmol/L
• HbA1c: 4 to 6.5%
• Normal supine blood pressure and normal ECG recordings

Exclusion Criteria:

• Female with child-bearing potential
• Evidence of clinically-significant renal, cardiac, bronchopulmonary, vascular, gastrointestinal, allergic, neurologic, metabolic (diabetes, thyroid disorders, adrenal disease), immunodeficiency disorders, cancer, hepatitis or cirrhosis.
• Intake of grapefruit or anything that may affect liver enzyme function within 1 month prior to the dosing day
• Clinically-relevant deviation from normal in the physical examination
• Subjects with a medical disorder, condition or history of such that would impair the subject's ability to participate or complete this study in the opinion of the investigator