Efficacy and Safety of Voglibose Compared With Acarbose in Participants With Type 2 Diabetes

Inclusion Criteria: 1. Has a historical diagnosis of type 2 diabetes mellitus (T2DM) for at least 6 months prior to the screening visit (V1). 2. Is male or female and aged from 18 to 75 years, inclusively. 3. Has a body mass index (BMI) between 20 and 45 kg/m\^2, inclusively. 4. Is experiencing inadequate glycemic control with a glycosylated hemoglobin (HbA1c) concentration between 7.0% and 10.0%, inclusively. 5. Has been treated with Metformin for at least 3 months and at a stable dose (≥1000 mg/day) for at least 8 weeks prior to Screening, unless there is documentation that the participant's current dose is his or her maximum tolerated dose (MTD) and MTD is ≤1000 mg/day. 6. Keeps constant body weight with fluctuation range no more than 10% over for at least 3 months before screening. 7. Hemoglobin levels of the participant are ≥12 g/dL (≥120 g/L) in male and≥ 10 g/dL (≥100 g/L) in female at screening visit. 8. Male serum creatinine \<1.5 mg/dL and female serum creatinine \<1.4 mg/dL, or estimated glomerular filtration rate (eGFR) \>60 ml/min/1.73m\^2 based on calculation using the Modification of Diet in Renal Disease (MDRD) approximation at Screening. 9. In the opinion of the investigator, the participant is capable of understanding and complying with protocol requirements. 10. The participant or, when applicable, the participant's legally acceptable representative signs and dates a written informed consent form and any required privacy authorization prior to the initiation of any study procedures. Exclusion Criteria: 1. Type 1 diabetes mellitus. 2. Has received insulin, voglibose, acarbose or other oral hypoglycemic drugs (except Metformin) for accumulative total of more than 7 days within the latest 3 months prior to Visit 1. 3. Has a history of cardiovascular disease: acute myocardial infarction, class III or IV heart failure, or cerebrovascular accident (stroke) within the latest 3 months prior to Visit 1. 4. The participant's liver function is damaged and has a significant clinical sign or symptom of hepatopathy, acute or chronic hepatitis, or the value of alanine aminotransferase (ALT) or aspartate aminotransferase (AST) is 3 times more than the upper limit of normal level at Visit 1. 5. Has an active proliferative retinopathy or macular degeneration that need to have an urgent treatment in the opinion of investigators. 6. Has a frequent attack of hypoglycemia or loses consciousness due to hypoglycemia in the opinion of investigators. 7. Has one or more times ketoacidosis or hyperosmotic status/coma. 8. Is receiving long-term (\>14days) systemic glucocorticoid treatment (except the medicine: local, intraocular, inhalation or via the nose) or has received such treatment for 4 weeks at Visit 1. 9. Has a hematopathy (e.g. hemolytic anemia, drepanocytosis) that may interfere with the HbA1c test. 10. Has other liabilities (e.g. drug abuse, alcoholism or mental disorder) that may hinder the participant to follow and complete the study. 11. Has participated in another clinical study within the past 90 days or has received any investigational compound within 30 days prior to randomization. 12. Is unsuitable for this study in the opinion of investigators. 13. Has a disease need to use other taboo or caution drugs that is not listed in this study. 14. If female, is pregnant or lactating or intending to become pregnant before, during, or within 30 days after participating in this study.