Treatment diaries will be asked for every subject to record glucose levels (7 times per day and 2 days per week for the first three weeks, then 7 times per day and 1 day per week until the end of this study), diet and exercise, stress situation, hypoglycemic symptoms and so on. All patients will be followed by visiting clinic every week for the first three weeks, but only patients in repaglinide group will be titrated their doses. Dose adjustment should be aimed at achieving the following glycemic targets: fasting blood glucose: 4.4 - 6.0 mmol/L, 2h post prandial glucose 4.4 - 8.0 mmol/L. If above glycaemic target has not been achieved, repaglinide dose should be adjusted for every week (see Schematic diagram of trial design). The adjustment of repaglinide doses is based on the mean of blood glucose recorded in subject diaries. The doses of repaglinide before each meal may be different, depending on the recorded blood glucose concentrations. After three weeks titration for repaglinide (maximal dosage for repaglinide is 2 mg tid), the patients in this group will keep the optimal dosage for the next 12 weeks. Clinic visit will be conducted every four weeks after the period of dosages titration to collect information, such as hypoglycemia, adverse events and fasting blood glucose.