Weight loss surgery has been around for more than sixty years now, and over the years the procedure has evolved in line with the trend of the times and is liked by the public. But who knows that the unique advantage of bariatric surgery to treat diabetes was actually an unexpected event back then. The original purpose of bariatric surgery was simply to lose weight. In 1982, a surgeon inadvertently discovered an inevitable relationship between bariatric surgery and the treatment of diabetes, and it was only after in-depth discussions and analysis of surgical data, and after years of clinical research and observation, that bariatric surgery was proven to be an effective treatment for diabetes. Just as weight loss surgery for diabetes was unexpected, no one could have imagined that the number of people with diabetes has skyrocketed worldwide in today’s context, especially in a country with a large population base like ours. In the context of the current situation, this can be called: an unexpected discovery for the benefit of mankind. The pathogenesis of diabetes has always been a question worthy of medical discussion, and what can be determined is that obesity is closely related to type 2 diabetes. Weight loss surgery can effectively reduce the amount of food intake in the human body. The intake of sugar in the human body mainly comes from daily eating, and the reduction of food intake after surgery can directly reduce the intake of sugar, which plays a certain role in the maintenance of blood sugar in the human body. At the same time, weight loss surgery can improve the body’s insulin resistance formed by obesity and restore the function of the pancreas, which is the key to long-term effective treatment of diabetes. Therefore, weight loss surgery can treat obesity type 2 diabetes although it is unexpected but in reason.