Background: We previously reported improved overall survival (OS) associated with metformin usage in a retrospective study of type 2 diabetes mellitus (DM) patients with colorectal (CRC) (Br J Cancer 2012;106:1374-8). We sought to determine whether this effect could be validated in an independent data set. Methods: Under an IRB-approved protocol, 6,128 patients with CRC based on ICD-9 billing codes diagnosed between 1995-2005 were reviewed; of these 683 were determined to have type 2 DM. Results: Of the 683 diabetic CRC patients, 407 (59.5%) were male. The patient’s stage at diagnosis was: stage I (67, 9.8%), II (162, 23.7%), III (247, 36.1%), IV (166, 24.3%) and unknown stage (41, 6%). The number of patients using metformin at the time of first evaluation was 146 (21.3%). A significantly better median OS was observed in CRC patients with metformin use in both all-stage and stage III groups (p = 0.017, p = 0.029 respectively); median OS results demonstrated in table below. Conclusions: This independent retrospective data set validated the OS benefit associated with metformin use previously reported in patients with type 2 DM and CRC. Future prospective studies will be required to confirm the benefit of metformin in this clinical setting.