Effectiveness and Safety of Adding Compound Preparation of Pioglitazone and Metformin for Type 2 Diabetic Patients

Inclusion Criteria: * Type 2 diabetic patients (WHO criterion, 1999) * 19kg/m2 ≤ BMI ≤ 35kg/m2 * Subject with the initial treatment of SUs on the basis of controlling diet and sport; treatment lasting for no less than 3 months and stable dose for at least 1 month; HbA1c 7-11% * No insulin therapy during 6 months before being selected * Not involved in any drug test during 3 months before being selected * No serious heart, liver or kidney diseases * Must have effective contraception methods for women of child-bearing age * Willing to being informed consent Exclusion Criteria: * Type 1 diabetes or other specific types of diabetes * Pregnancy, preparation for pregnancy, lactation and women of child-bearing age incapable of effective contraception methods * Uncooperative subject because of various reasons * Abnormal liver function, glutamic-pyruvic transaminase (ALT) and glutamic-oxaloacetic transaminase (AST) \> twice the upper limits of normal * Impairment of renal function, serum creatinine: ≥ 133mmol/L for female，≥ 135mmol/L for male * Serious chronic gastrointestinal diseases * Edema * Serious heart diseases, such as cardiac insufficiency (level III or more according to NYHA), acute coronary syndrome and old myocardial infraction * Blood pressure: Systolic blood pressure (SBP) ≥ 180mmHg and/or diastolic blood pressure (DBP) ≥ 110mmHg * White blood count (WBC) \< 4.0×109/L or platelet count (PLT) \< 90×109/L，or definite anemia (Hb：\< 120g/L for male, \< 110g/L for female), or other hematological diseases * Endocrine system diseases, such as hyperthyroidism and hypercortisolism * Experimental drug allergy or frequent hypoglycemia * Psychiatric disorders, drug or other substance abuse * Diabetic ketoacidosis and hyperosmolar nonketotic coma requiring insulin therapy * Stressful situations such as surgery, serious trauma and so on * Chronic hypoxic diseases such as pulmonary emphysema and pulmonary heart disease * Combined use of drugs effecting glucose metabolism such as glucocorticoid * Tumor, especially bladder tumor and/or family history of bladder tumor and/or long-term hematuria