Obesity and related metabolic disorders are increasing especially in developing countries. It is widely accepted that in extremely obese patients bariatric surgery reduces body weight and improves type 2 diabetes and the metabolic syndrome. Weight loss partially explains this effect as do weight loss-independent mechanisms linked to gut hormones, peptide YY, ghrelin, glucagon-like peptide-1, and glucose-dependent insulinotropic peptide/gastric inhibitory polypeptide. Several groups performing established and novel surgical techniques have shown encouraging metabolic results. Herein we consider whether it is theoretically plausible to use surgery as an alternative or complementary approach to medical treatment of diabetes in overweight and mildly obese patients. © 2010 The Author(s).