Resource-poor primary health settings in an urban slum presented with special challenges in diabetes care. The study evaluated a need-based, patient-friendly, acceptable, appropriate package of care and its implementation in primary healthcare setup. An open-label two-arm parallel randomized controlled trial with 40 patients in the control group who received medical management as prescribed by physician and patients in the intervention group receiving usual medical care + group-based comprehensive diabetes management program. HbA1c, weight, BMI, Quality of Life Instrument for Indian Diabetes Patients (QOLID) scores, and audit of Self Care Inventory-Revised Version (SCI-R) were assessed at baseline and 6 months. There was a significant reduction in mean HbA1c levels in the intervention arm (8.44, SD = 1.802 to 7.56, SD = 1.87) as compared with the control arm (8.4, SD = 1.87 to 8.19, SD = 1.77). Multiple linear regression model (R2 = 0.886, ANOVA F (7, 72) = 79.733, p < 0.001) found a fall in blood sugar levels (β = − 0.511, p < 0.001), improvement in QOLID scores (β = 0.221, p = 0.004), increase in physical activity (β = 0.198, p = 0.006), and fall in BMI (β = 0.153, p = 0.009) to be predictive of change in HbA1c. The patient profile consisted predominantly of homemakers, with low formal education and belonging to lower socio-economic strata. They depended primarily on the public health system for their health care needs and could benefit most from the implementation of the program. There was an improvement in knowledge, regular follow-up, compliance to medication, diet, and physical activity along with improvement in glycemic control, self-care behavior and quality of life of patients in the intervention arm.