Type 2 diabetes mellitus is associated with obesity, dyslipidemia, and hypertension, all well-known risk factors for cardiovascular disease. Surgical weight loss has resulted in a marked reduction of these risk factors in adults. We hypothesized that gastric bypass would improve parameters of metabolic dysfunction and cardiovascular risk in adolescents with type 2 diabetes mellitus. Eleven adolescents who underwent Roux-en-Y gastric bypass at 5 centers were included. Anthropometric, hemodynamic, and biochemical measures and surgical complications were analyzed. Similar measures from 67 adolescents with type 2 diabetes mellitus who were treated medically for 1 year were also analyzed. Adolescents who underwent Roux-en-Y gastric bypass were extremely obese (mean BMI of 50 +/- 5.9 kg/m(2)) with numerous cardiovascular risk factors. After surgery there was evidence of remission of type 2 diabetes mellitus in all but 1 patient. Significant improvements in BMI (-34%), fasting blood glucose (-41%), fasting insulin concentrations (-81%), hemoglobin A1c levels (7.3%-5.6%), and insulin sensitivity were also seen. There were significant improvements in serum lipid levels and blood pressure. In comparison, adolescents with type 2 diabetes mellitus who were followed during 1 year of medical treatment demonstrated stable body weight (baseline BMI: 35 +/- 7.3 kg/m(2); 1-year BMI: 34.9 +/- 7.2 kg/m(2)) and no significant change in blood pressure or in diabetic medication use. Medically managed patients had significantly improved hemoglobin A1c levels over 1 year (baseline: 7.85% +/- 2.3%; 1 year: 7.1% +/- 2%). Extremely obese diabetic adolescents experience significant weight loss and remission of type 2 diabetes mellitus after Roux-en-Y gastric bypass. Improvements in insulin resistance, beta-cell function, and cardiovascular risk factors support Roux-en-Y gastric bypass as an intervention that improves the health of these adolescents. Although the long-term efficacy of Roux-en-Y gastric bypass is not known, these findings suggest that Roux-en-Y gastric bypass is an effective option for the treatment of extremely obese adolescents with type 2 diabetes mellitus.