Bariatric surgery can help with weight loss, but it may also help eliminate or reduce the effects of type 2 diabetes.
A 2024 JAMA study reported surgery was more effective in controlling type 2 diabetes in people with obesity than medication and lifestyle changes.
According to the study, surgery led to more weight loss and better blood sugar control in the long term. It also led to more long-term remission of type 2 diabetes than medication and lifestyle changes. Surgery was also safe for patients in the long run.
The findings led to surgery becoming more common as a treatment for type 2 diabetes in people with obesity. Before this study, there hadn’t been a multisite study comparing the long-term results of conventional medical therapy to multiple bariatric surgical procedure options.
“This study is the strongest evidence we have to date to support the use of bariatric and metabolic surgery to treat diabetes in people with Class 1, Class 2, and Class 3 obesity,” says Anita Courcoulas, MD, chief, Minimally Invasive Bariatric and General Surgery, UPMC, and the study’s lead author.
“I think what’s important about this study is it’s kind of a landmark study in that it really gives very firm, high-level, high-quality data to show that surgery is an effective and durable treatment.”
Is There a Link Between Obesity and Diabetes?
Obesity — having a body mass index (BMI) of 30 or higher — is a risk factor for type 2 diabetes. About 90% of people with type 2 diabetes also struggle with obesity or being overweight, according to the American Society for Metabolic and Bariatric Surgery.
Obesity has three classes:
- Class 1: BMI of 30 to 34.9.
- Class 2: BMI of 35 to 39.9.
- Class 3: BMI of 40 and higher.
“In the United States, the number of people that have both type 2 diabetes and Class 1 obesity is about 26 million people,” Dr. Courcoulas says. “Those numbers are changing every year, and sadly, they’re not going down. They’re going up.”
Type 2 diabetes can lead to cardiovascular problems like heart attack and stroke. It also can cause other complications, including problems with the eyes, kidney function, and blood circulation.
“Diabetes has a really strong negative effect on people’s long-term health because of these vascular consequences,” Dr. Courcoulas says. “The mortality of people who have diabetes and obesity is higher than people who don’t.”
Getting effective treatment for type 2 diabetes is critical to avoid complications.
Bariatric Surgery vs. Conventional Medical Therapy for Diabetes
The conventional medical therapy for controlling type 2 diabetes in people with obesity includes a combination of medication and lifestyle changes. People receive the best available medications to control diabetes.
They also get encouraged to eat healthy and exercise more. A healthy diet and exercise can help people to better manage both their weight and their diabetes.
In recent years, surgery has emerged as a potential treatment for type 2 diabetes in people with obesity. The American Society for Metabolic and Bariatric Surgery says surgery is a possible treatment option for people with Class 1 obesity and type 2 diabetes.
When used as a treatment for diabetes, “bariatric surgery” is known as metabolic surgery.
Is Bariatric/Metabolic Surgery Good for Type 2 Diabetes?
According to the study in JAMA, surgery can help people with obesity control their type 2 diabetes better than conventional medical therapy can.
The multisite study, which began in 2007, followed 262 patients from four different medical centers, including UPMC. The patients all had obesity and type 2 diabetes.
The participants were randomly assigned into two groups. One group received conventional medical therapy — the best available medications, along with lifestyle changes and counseling. The other group had one of three types of metabolic surgery:
- Adjustable gastric banding.
- Roux-en-Y gastric bypass.
- Sleeve gastrectomy.
Researchers followed up with the participants at seven and 12 years. At both seven and 12 years, the participants who underwent metabolic surgery showed better control of their diabetes. They had better blood sugar control, took fewer diabetes medications, and had higher remission rates than those in the nonsurgical group.
The surgical group also had higher weight loss and lower cholesterol over time.
“When you look at this and other studies, they show that the majority of weight loss with bariatric surgery is maintained over time,” Dr. Courcoulas says. “It’s durable, and it’s associated with health improvements like type 2 diabetes and cholesterol improvement.”
Can surgery cure type 2 diabetes?
Bariatric/metabolic surgery isn’t a guaranteed way to “cure” diabetes. However, the JAMA study showed people with obesity who underwent metabolic surgery had a higher remission rate of their type 2 diabetes than people who had conventional medical therapy. That means their glycated hemoglobin (A1C) levels were below 6.5% without taking medications.
According to the study, 12.7% of people who underwent surgery had diabetes remission 12 years after surgery. In comparison, no members of the nonsurgical treatment group had diabetes remission 12 years after surgery.
Which Bariatric Surgery Is Best for Diabetes?
Patients in the surgical group for the JAMA study underwent gastric bypass, gastric sleeve, or gastric banding. Because of the study’s size, it couldn’t fully determine which surgery was best for diabetes. But gastric bypass and gastric sleeve both showed better results for diabetes improvement and weight loss than gastric banding did.
“We’ve seen that in practice because the gastric band is no longer used because it had less weight loss,” Dr. Courcoulas says. “So, it appears that the two common bariatric operations of today are the more effective operations for both diabetes improvement and weight loss.”
Is Bariatric Surgery Safe for Diabetes?
The JAMA study showed surgery was as safe as conventional medical therapy for people with obesity and type 2 diabetes. There was an equal number of deaths in each group over time. There were also no differences in cardiovascular outcomes like heart attack or stroke.
People in the surgical group did have higher rates of anemia and bone fractures than the nonsurgical group. This is possibly because surgery sometimes leads to deficiencies in vitamins and minerals. People in the surgical group also had more gastrointestinal side effects like nausea and abdominal pain.
People in the nonsurgical group had more problems with gastroparesis (paralysis of the stomach), which is a potential complication of diabetes. The nonsurgical group also had more people who ended up on dialysis for kidney disease.
Overall, Dr. Courcoulas says it was encouraging to see no other major safety differences between the surgery and non-surgery group.
“It’s very reassuring to see that surgery is safe over the long run,” she says. “We do know that we have to monitor people’s micronutrients because iron deficiency is common after these operations, as are some other micronutrient deficiencies.
“But the long-term safety in terms of the big things like death, heart attack, stroke, and other major adverse outcomes looks very positive for surgery as a safe and effective treatment.”
People who undergo bariatric/metabolic surgery also have to commit to a lifestyle that includes a healthier diet and exercise. They may need to take vitamin and mineral supplements. But they can live a healthy life after surgery and face fewer long-term health complications.
Should I Consider Surgery for Type 2 Diabetes?
If you have Class 1 obesity or higher and type 2 diabetes, talk to your doctor about treatment options. These may include surgery.
Bariatric surgery has long been an option for weight loss. The JAMA study shows it’s also an effective treatment for diabetes.
New medications for diabetes and weight loss have emerged in recent years. These include glucagon-like peptide-1 (GLP-1) agonists. Dr. Courcoulas says a potential next step in research would be comparing bariatric/metabolic surgery to these new medications.
“The big outstanding question about these new GLP-1 medications is if the results are going to be durable over time,” she says. “It appears people have to stay on the medications to keep the weight off over the long run. Whereas with the bariatric or metabolic surgery option, you have the operation and then there’s the ability to keep the weight off and keep the health improvements going for a long period of time.”
UPMC Bariatric Services holds the highest national accreditation for bariatric centers. We offer a wide range of surgical and nonsurgical services. For more on our services, visit our website.