Objective: To evaluate the effect of a community-based intervention supporting type 2 diabetes mellitus patients in their self-management of the disease. Methods: This research was a randomized controlled trial conducted in communities in Fangshan District, Beijing, China. Adult patients with type 2 diabetes from 17 communities in 4 sub-district of Fangshan District were randomly assigned to either the intervention or control group. Participants in the intervention group participated in a three-month group-based diabetes self-management intervention service. Data were collected both in intervention and control group at baseline and after the intervention to evaluate the effect of the intervention. A questionnaire survey was completed by all participants to collect their demographic information, diabetes related health behaviors and skills. A physical examination and lab testing including height, weight, blood pressure, and waist circumference as well as HbA1c, fasting blood glucose, lipid profile were conducted before and after the intervention. Results: A total of 500 valid questionnaires were received, including 259 in the intervention group and 241 in the control group. Patients in the intervention group who learned how to conduct the self-monitoring of blood glucose increased from 56.76% ( n =147) to 87.26% ( n =226) after the intervention, higher than that of control group (63.07%, n =152) ( P< 0.001). 69.50% ( n =180) patients in intervention group had blood glucose monitor at home, which was 60.62% ( n =157) prior to the intervention and higher than that of control group (57.68%, n =139) ( P= 0.004). After the intervention, 3.09% ( n =8) patients in intervention group ceased to take medicine by themselves, which was 16.22% ( n =42) before the intervention, while the control group was 8.30% ( n =20) after the intervention ( P= 0.009). Patients in the intervention group made significant improvements in implementing self monitoring on blood glucose (SMBG), which was increased from one day per week to 2 days per week, and foot self-examination, which increased from 2 days per week to 7 days per week. The body weight of patients in the intervention group reduced 1.62 kg on average after the intervention, while it increased 0.88 kg in the control group. Similar improvement was found in waist circumstance between the intervention and control group (-0.83 cm vs -0.16 m). There was a significant reduction on body weight and waist circumstance in the intervention group ( P< 0.05). Conclusion: The group activities focusing on people with type 2 diabetes resulted in improvement in their lifestyle and self management behaviors, as well as their body weight and waist circumstance.