If someone is severely overweight and diets and exercise haven’t worked, surgery to shrink the stomach can be a next step to help them lose weight and feel better.

When very overweight people have weight-loss surgery, many of them stop needing diabetes medicine within months—even before they lose a lot of weight—because their body starts using insulin better and their gut sends out helpful signals. About a third to almost half still stay diabetes-free five years later.

After bariatric surgery, people who lose more than 30% of their total weight loss as fat-free mass (such as muscle) by three months are more likely to develop metabolic problems and have lower physical function.