To investigate the Safety and Efficacy of Acarbose+Saxagliptin Compared With Metformin+Saxagliptin in Patients With Type 2 Diabetes,100 patients with T2DM will be enrolled in this study.They will randomly be assigned to Acarbose+Saxagliptin or Metformin+Saxagliptin group.HbA1c，fasting and postprandial C-peptide will be observed before and after the interventions.

Participants coming on study will be assigned to two groups：Acarbose+Saxagliptin and Metformin+Saxagliptin. It may take 1 weeks to be stabilize to a standardized dose, and then the investigators will follow-up the patients for 3 months.During the period,patients will be asked to come back to the investigators center to receive the related examination every month. The investigators will detect HbA1c，fasting and postprandial C-peptide before and after the interventions.

Inclusion Criteria:

• Newly diagnosed type 2 diabetes mellitus（course of disease less than one year） who has not receive drug treatment.
• T2DM patients who has not receive drug treatment for three months at least.
• HbA1c for 7.5-10%.

Exclusion Criteria:

• New or worsening signs or symptoms of coronary heart disease
• Medical history of active liver disease and kidney disease
• Poorly controlled hypertension（systolic blood pressure>160mmHg or diastolic blood pressure>95mmHg）
• A clinically important hematological disorder
• A history of intolerance or hypersensitivity or any contraindication to study medications (including saxagliptin, metformin, acarbose)
• Is pregnant or breast feeding or is expecting to conceive or donate eggs
• A medical history of drug abuse
• Can not be followed -up on time
• Endocrinological diseases（eg： hyperthyroidism、hypothyroidisn and cushing syndrom）
• Gastrointestinal diseases
• Mental disorser
• Hypoxic disease