Bariatric surgery was initially developed as a tool for weight reduction only, but it is gaining popularity because of its remarkable effect on glucose metabolism in morbidly obese and less obese patients. Recent publications have shown the superiority of metabolic surgery over medical treatment for diabetes, creating a new field of clinical research that is currently overflowing in the medical community with outstanding high-quality data. Metabolic surgery is effective in treating diabetes, even in non-morbidly obese patients.