To evaluate the independent effects of peer support , we further used a case-control design to. Within the 1200 patients who were not offered peer support, a group of patients who met the criteria of "high risk" were matched to those agreed to receive peer support on a 3:1 basis by age, gender, diabetes duration, and baseline HbA1c as a control group. Data of metabolic control and hospitalization of the control group were retrieved from the CMS and compared to that of the peer group after 1 year.