A variety of studies have previously shown that bariatric surgery is a highly effective treatment for diabetes. But new research expands the role of these surgeries to include prevention of the disease: obese people who undergo bariatric surgery are four times less likely to develop type 2 diabetes, according to research published in the New England Journal of Medicine. Using data from the Swedish Obese Subjects (SOS) study, researchers compared 1658 patients who received bariatric surgery and 1771 matched patients who received standard treatment for obesity (control group). Of the patients in the bariatric surgery group, 19 percent underwent gastric banding, 69 percent vertical banded gastroplasty, and 12 percent gastric bypass. None of the patients had diabetes at the start of the study.
The researchers found that 10 years after surgery, 28 percent of the patients in the control group had developed diabetes. In the surgery group, just 7 percent of the patients had developed diabetes. This translates to almost an 80 percent reduction in risk of developing diabetes after bariatric surgery. At 15 years, 38 percent had developed diabetes in the control group, compared to 13 percent the surgery group. The risk of developing diabetes was about one in 150 per year for the surgery group, compared to one in 35 per year in the control group. Even though the patients who underwent surgery initially were a bit heavier and had more risk factors for developing diabetes, their 10 and 15-year outcomes were much more favorable. Additionally, 10 and 15 years, the surgery group’s average weight loss was more than 6 times greater than the control group (who received standard counseling about the importance of eating well and exercising).
Dr. Jaime Ponce, expert weight loss surgeon at Chattanooga Bariatrics and president of the ASMBS told us, “this is great new evidence showing us that bariatric surgery not only is the most effective therapy to treat type 2 diabetes in obese patients, but also is very effective at preventing it.” Additionally, Ponce said, “Bariatric surgery, compared with usual medical care, reduced the long-term incidence of type 2 diabetes significantly in obese patients. And this effect was true for all types of procedures.”
The researchers reported that the effect of bariatric surgery was influenced by the presence or absence of impaired fasting glucose. In people who already had rising blood-sugar levels, those who received bariatric surgery decreased their risk of diabetes by 87 percent. Dr. Ponce highlighted this finding: “The other important finding was that BMI did not influence the prevention outcome, but impaired fasting glucose did. This suggests that disturbances of glucose metabolism might need to be treated early, even before type 2 diabetes is diagnosed.”
The study authors point out that their research is not a clinical trial; for ethical reasons, participants were not randomly given standard treatment or bariatric surgery because at the time the study began in the 1980’s, surgery carried a 5 percent risk of death. (Today’s surgery techniques are much safer, but not completely risk-free.) Previous research has focused on the effectiveness of weight loss surgery in improving type 2 diabetes, but this is one of the first large studies to address how surgery can prevent development of diabetes.
You can read more about how surgery has been shown to improve diabetes here.