[Clinical evidence for metabolic surgery].

The metabolic effect of bariatric surgery is well-established and is considered to be self-evident in morbidly obese patients with a body mass index (BMI) > 40 kg/m(2). Metabolic surgery performed on patients with obesity grades II (BMI 35-40 kg/m(2)) and I (BMI 30-35 kg/m(2)) according to the World Health Organization (WHO) has increased in recent years; however, the indications for metabolic surgery in obesity grades I and II are currently under debate due to insufficient evidence. In the last 5 years several highly qualified randomized clinical trials have been published which evaluated the effect of metabolic surgery in patients with obesity grades I and II in comparison to conservative therapy. Based on these data the efficacy of metabolic surgery in short-term follow-up (12-36 months) is unquestionable when compared to conservative therapy according to the current guidelines. Besides improved glycemic control and remission of diabetes, metabolic surgery has the potential to have a positive influence on diabetic complications, such as diabetic retinopathy, nephropathy and polyneuropathy, as well as on comorbidities, such as arterial hypertension and dyslipidemia. Future clinical trials should address the long-term (> 36 months) effects of metabolic surgery, patient selection criteria and choice of procedure.