Intervention of Type 2 DM with Sitagliptin or High dose Metformin Trial in Kobe: INSIGHT-KOBE

INTERVENTION: start with Sitagliptin 50 mg/day and up to 100 mg/day start with Metformin 500 mg/day and up to 1500 mg/day CONDITION: Type 2 Diabetes Mellitus PRIMARY OUTCOME: change in CPR index during 3years SECONDARY OUTCOME: 1. duration to monotherapy failure; 2. HbA1c, MAGE obtained from SMBG; 3. new onset or progression of micro, macrovascular complication; 4. HOMA beta, HOMA‐R, proinsulin/insulin ratio; 5. adverse event and body weight change INCLUSION CRITERIA: 1. treated only with life style modification (or cesssation of previous treatment for more than 1 month) 2. obtained documented agreement 3. patients between 20 and 35 4. HbA1c (JDS) between 6.5% and 8.0%