Three-Arm Comparative Study of Miglitol and Mitiglinide Alone and in Combination -Efficacy and Safety Studies-

INTERVENTION: Miglitol 150mg/day Mitiglinide 30mg/day Miglitol 150mg/day + Mitiglinide 30mg/day CONDITION: type 2 diabetes mellitus PRIMARY OUTCOME: Glycemic control ; meal‐loading tests:plasma glucose, serum insulin, total GLP‐1, total GIP ; HbA1c, 1,5‐AG SECONDARY OUTCOME: high‐molecular weight adiponectin, high sensitivity C reactive protein (hs‐CRP),; 8‐Hydroxydeoxyguanosine(8‐OhdG), INCLUSION CRITERIA: (1)Patients with type 2 diabetes whose HbA1c (NGSP) was >= 6.5% but < 8.4% during prior treatment (2)Patients who are undergoing dietary/exercise therapy or biguanide therapy in addition to dietary/exercise therapy (3)Age >= 20 years (4)Patients who have the ability to provide written informed consent personally