© 2018 American Medical Association. All rights reserved. IMPORTANCE Because of the substantial increase in the occurrence of type 2 diabetes in the pediatric population and the medical complications of this condition, therapies are urgently needed that will achieve better glycemic control than standard medical management. OBJECTIVE To compare glycemic control in cohorts of severely obese adolescents with type 2 diabetes undergoing medical and surgical interventions. DESIGN, SETTING, AND PARTICIPANTS A secondary analysis of data collected by the Teen-Longitudinal Assessment of Bariatric Surgery (Teen-LABS) and Treatment Options of Type 2 Diabetes in Adolescents and Youth (TODAY) consortia was performed. Teen-LABS enrolled 242 adolescents (-19 years of age) from March 1, 2007, through December 31, 2011. TODAY randomized 699 participants (aged 10-17 years) from July 24, 2004, through February 25, 2009. Data analysis was performed from July 6, 2015, to June 24, 2017. Anthropometric, clinical, and laboratory data from adolescents with severe obesity and type 2 diabetes who underwent treatment with metabolic or bariatric surgery in the Teen-LABS study or medical therapy in the TODAY study were compared. INTERVENTIONS Teen-LABS participants underwent a primary bariatric surgical procedure; TODAY participants were randomized to receivemetformin therapy alone or in combination with rosiglitazone or an intensive lifestyle intervention; insulin therapy was given in cases of progression of disease. MAIN OUTCOMES AND MEASURES Glycemic control, body mass index, prevalence of elevated blood pressure, dyslipidemia, abnormal kidney function, and clinical adverse events were measured. RESULTS Data from 30 participants from Teen-LABS (mean [SD] age at baseline, 16.9 [1.3] years; 21 [70%] female; 18 [66%] white) and 63 from TODAY (mean [SD] age at baseline, 15.3 [1.3] years; 28 [44%] female; 45 [71%] white) were analyzed. During 2 years, mean hemoglobin A1c concentration decreased from 6.8%(95%CI, 6.4%-7.3%) to 5.5%(95%CI, 4.7%-6.3%) in Teen-LABS and increased from 6.4%(95%CI, 6.1%-6.7%) to 7.8%(95%CI, 7.2%-8.3%) in TODAY. Compared with baseline, the body mass index decreased by 29% (95%CI, 24%-34%) in Teen-LABS and increased by 3.7%(95%CI, 0.8%-6.7%) in TODAY. Twenty-three percent of Teen-LABS participants required a subsequent operation during the 2-year follow-up. CONCLUSIONS AND RELEVANCE Compared with medical therapy, surgical treatment of severely obese adolescents with type 2 diabetes was associated with better glycemic control, reduced weight, and improvement of other comorbidities. These data support the need for a well-designed, prospective controlled study to define the role of surgery for adolescents with type 2 diabetes, including health and surgical outcomes.