Obesity and diabetes are chronic diseases frequently linked together. Durable weight loss is uncommon with medical/behavioral approaches. For severe obesity, bariatric surgery is the only treatment resulting in sustained weight loss. Bariatric surgery may be considered for adults with BMI ≥ 35 kg/m² and type 2 diabetes, especially if the diabetes or associated comorbidities are difficult to control with lifestyle and pharmacological therapy. Bariatric surgery reduces the incidence of diabetes in overweight insulin-resistant subjects and is associated with remission of diabetes in a large proportion of patients. In considering the usefulness of bariatric surgery, it is also important to recognize that long-term follow-up is required before assigning a beneficial therapeutic effect in patients with diabetes because of the potential for weight regain that has been observed. As diabetes is a lifelong disease, it is important to emphasize that a certain percentage of patients will suffer from relapse of their diabetes.