Bariatric surgery was developed with the aim of weight reduction. Success was defined only by excess weight loss. Other indices of resolution of metabolic comorbidities were reported, but were mostly secondary. Several communications have reported that regardless of body mass index (BMI), complete or partial remission of type 2 diabetes mellitus (T2DM) is possible. These results mostly occur before weight loss, positioning metabolic surgery as a good tool for controlling the current T2DM epidemic. Medical treatment is evolving, but is expensive and not risk-free. Surgery aimed mainly at diseases such as diabetes and not weight loss are referred to as "metabolic surgery." Metabolic surgery has been proven to be safe and effective, and although more data are needed, it is unquestionable that a new discipline has been founded. Metabolic surgery can effectively treat T2DM in individuals with any BMI, including that below 35 kg/m(2).