Objective: To compare the relative efficacy of medical management, the duodenal switch (DS), and the laparoscopic adjustable gastric band (LAGB) to the Roux-en-Y gastric bypass (RYGB) for treatment of type 2 diabetes mellitus (T2DM). Background: The RYGB resolves T2DM in a high proportion of patients and is considered the standard operation for T2DM resolution in morbidly obese patients. However, no data exist comparing the efficacy of medical management and other bariatric operations to the RYGB for treatment of T2DM in comparable patient populations. Methods: We performed a retrospective case-matched study of morbidly obese patients with T2DM who had undergone medical management (nonsurgical controls [NSC]; N = 29), LAGB (N = 30), or DS (N = 27) and were compared with matched T2DM patients who had undergone RYGB. Matching was performed with respect to age, sex, body mass index, and hemoglobin A1C (HbA 1C). Outcomes assessed were changes in body mass index, HbA 1C, and diabetes medication scores at 1 year. Results: The Roux-en-Y gastric bypass produced greater weight loss, HbA 1C normalization, and medication score reduction compared to both NSC and LAGB-matched cohorts. Duodenal switch produced greater reductions in HbA 1C and medication score than RYGB, despite no greater weight loss at 1 year. Surgical complications were rarely life threatening. Conclusions: This study provides an important perspective about the comparative efficacy of LAGB, DS, and NSC to the RYGB for treatment of T2DM among obese patients. After 1 year of follow-up, RYGB is superior to NSC and LAGB with respect to weight loss and improvement in diabetes whereas DS is superior to RYGB in reducing HbA 1C and medication score.