More than 2.5 billion adults around the world are either overweight or obese. Many of them develop serious health conditions, such as type 2 diabetes. One of the most effective ways to lose a large amount of weight and reduce health risks is bariatric surgery.
This type of surgery changes the digestive system to help people eat less and absorb fewer calories. But not everyone benefits from it in the same way, especially people who don’t yet have diabetes.
A new international study looked at whether we can predict who will benefit the most from bariatric surgery by looking at their risk level for developing diabetes. Researchers from Germany, France, and Italy studied people with obesity who had not yet developed type 2 diabetes, but who were at risk.
They grouped the participants based on diabetes risk “subtypes”—which are categories that describe how likely someone is to get diabetes based on their weight, metabolism, and other factors.
The study included two main groups. One group had surgery in hospitals in Lille, France, and Rome, Italy. Another group in Tübingen, Germany, did not have surgery but instead tried to improve their health through changes in lifestyle, like healthier eating and more exercise.
The scientists then compared how well each group improved in terms of blood sugar control, liver fat, insulin sensitivity, and other markers of metabolic health.
Before the surgery or lifestyle changes, all the participants were assigned to a diabetes risk subtype. Subtypes 5 and 6 had the highest risk of developing diabetes or related health problems.
Subtype 4 had a low risk, even though people in this group were also overweight or obese. Subtypes 1, 2, and 3 included people who were not severely overweight and had a lower risk.
The results showed that people in subtypes 5 and 6, the highest risk groups, had the most to gain from bariatric surgery. After surgery, they showed major improvements: their insulin sensitivity got better, their bodies were better at using insulin to manage blood sugar, and their beta cells (which produce insulin) worked more effectively.
Many people in these high-risk groups even had their prediabetes reversed—meaning their blood sugar returned to normal—and their liver fat levels dropped. Importantly, after surgery, most of these individuals were no longer considered high-risk.
Interestingly, the people in the control group who received lifestyle counseling and support lost a similar amount of weight compared to those who had surgery. But the health improvements weren’t as strong, especially in blood sugar control.
For example, even people in the low-risk group (subtype 4) who followed lifestyle advice did not see a high rate of prediabetes remission. This shows that simply losing weight may not be enough to improve certain health conditions, especially without the deep metabolic changes that happen after surgery.
This study highlights the importance of knowing someone’s diabetes risk subtype before recommending bariatric surgery. According to the researchers, this kind of personalized approach—called precision medicine—can help doctors choose the right treatment for each patient. People with high-risk subtypes may benefit much more from surgery than others.
In short, not all people with obesity are the same. Some face a higher risk of serious metabolic diseases like diabetes, and they may see the greatest improvements after bariatric surgery. Meanwhile, others who are overweight but have a lower diabetes risk may not experience the same level of health improvement, even if they lose weight.
This study could lead to better, more targeted care for people at risk of diabetes, helping doctors make more informed decisions about who should be recommended for surgery.
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The research findings can be found in Diabetes Care.
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