Bariatric Surgery Beats Lifestyle Changes for Type 2 Diabetes

7 min read

Feb. 28, 2024 – When Kristen Hugus was offered the chance to take part in a medical study that randomly assigned people with type 2 diabetes to have either bariatric surgery or intensive lifestyle coaching plus medication, she thought of her 4-year-old daughter.

“I had been just so tired all the time, and the summer before all this happened for me, I remember laying on the couch when it was a beautiful day outside and my daughter really wanting to do things, and I just didn’t have the energy,” she recalled. “So although it was a scary prospect of perhaps having a major surgery, the chance to be healthy, for me, was something that I just couldn’t pass up, because I wanted to be able to be a good example for my daughter.”

Hugus was randomly assigned for the study to have gastric bypass surgery, which is sometimes called weight loss surgery. That was in 2010, and shortly after, she no longer needed to use insulin to manage her blood sugar, and her blood sugar levels on the commonly used A1c test dropped into a much safer range. Over time, the 5-foot, 2-inch registered nurse had a 33% drop in her weight, from 188 pounds to about 125 pounds. 

Now 50 years old and living in a suburb outside Pittsburgh, Hugus has maintained those health benefits for more than 10 years. Her results, to a large extent, represent the study’s overall findings, which were published Tuesday in The Journal of the American Medical Association.

Researchers reported that the 166 patients who had bariatric surgery were significantly more likely to have improved glycemic control, diabetes remission, reduced cholesterol levels, and maintain much of their weight loss for a dozen years, compared to the 96 people treated with medical management and lifestyle changes based on approaches known as Look AHEAD and the Diabetes Prevention Program. It is the longest follow-up comparison to date of people with type 2 diabetes who were randomized to treatment using bariatric surgery vs. medical management/lifestyle. All of the people in the study had type 2 diabetes at first and had either overweight or obesity.

The study answers a long-standing question of whether surgical results can endure, similar to current questions about blockbuster weight loss drugs and whether they provide results that can last.

People whose treatment entailed lifestyle interventions received intensive nutrition counseling as well as behavioral counseling for at least a year. People in the surgery group had one of three types of bariatric surgery: gastric bypass, gastric sleeve, or banding, the latter of which is no longer commonly used. Bariatric surgeries modify the stomach or small intestine, affecting how many calories a person can consume or absorb.

After 7 years, 18% of surgery patients had achieved diabetes remission, compared to 6% of those in the medical/lifestyle group. But by the 12-year mark, no one in the lifestyle group was still in remission, while 13% in the surgery group remained so. But the remission rate for the surgery group was much higher (nearly 51%) after the first year, and the medical/lifestyle group, in contrast, improved their remission rate from less than 1% after the first year.

This suggests “that bariatric surgery is an effective intervention for better diabetes management, but the effects are not as sustainable as one had hoped for,” Neda Rasouli, MD, Diabetes and Endocrinology Clinical Trial Program director at the University of Colorado School of Medicine, said in an email. She was not involved in the study.

People in the lifestyle group were also treated with medications. Before surgery, nearly all of the people in the surgery group were also taking diabetes medications, but by a year after surgery, only 38% were still taking medications, although that rose to 61% after 7 years.

“So that’s really important to highlight. You can’t say that surgery takes everybody off all medications, forever. Surgery leads to improvement in glycemic control and improvement in diabetes remission and that improvement, other studies have shown pretty clearly, kind of have a legacy effect,” said the lead author of the study, Anita P. Courcoulas, MD, a professor of surgery at the University of Pittsburgh School of Medicine. “So if you even have a short period of diabetes remission and improved glycemic control, you are likely improving your chance of not developing microvascular and macrovascular diabetes complications, like heart attack, stroke, eye, foot, and renal complications.”

But Rasouli noted that the study didn’t find a reduced risk of problems with the heart and blood vessels among people in the surgery group, although that could have been due to some of the design aspects of the study.

After 12 years, the researchers reported that the average sustained weight loss was 19% for surgery patients and 11% for medical/lifestyle patients.

Importantly, researchers were able to look at a subgroup of people with lower body mass indexes, or BMIs, (down to 30), and found that this lower-BMI group had similar better outcomes from bariatric surgery, compared to the medical/lifestyle approach. (BMI is a measure of a person's body fat based on height and weight.) 

Breakthrough new treatments using a class of drugs called GLP-1 agonists were not a major part of the study because the investigations started between 2007 and 2013, before these new medicines, like Ozempic and Mounjaro, became popular. 

But because this study’s follow-up period was so long, many patients in both treatment groups did begin taking GLP-1 agonist medications eventually.

The study is known as the Alliance of Randomized Trials of Medicine vs. Metabolic Surgery in Type 2 Diabetes (ARMMS-T2D), and was funded by the National Institutes of Health. It began as four separate but similar studies that were later merged for analysis. The four research centers taking part in the project were the University of Pittsburgh, Cleveland Clinic, Joslin Diabetes Center and Brigham and Women’s Hospital, and the University of Washington and Kaiser Permanente Washington.

Because the study started as four separate ones, there are some limits to the results, Rasouli noted, such as the treatment approaches not being 100% identical and varying follow-up periods. Fewer people in the medical/lifestyle group took part in long-term follow-up, compared to those in the surgery group.

“Usually, participants who have not responded well to the intervention have a higher tendency of not joining the long-term follow up,” she said.

While the people in the surgery group tended to have better health outcomes, they were more likely than the people in the medical/lifestyle group to have adverse events after surgery, like anemia, fractures, and gut issues. The problems are not categorized by the medical community as serious. But, Courcoulas noted, "they're certainly important to a patient because they can cause symptoms for a patient.”

Tracking those side effects allows providers to inform patients ahead of time about what might happen after surgery, said Courcoulas, who is also chief of minimally invasive bariatric and general surgery at the University of Pittsburgh Medical Center.

Hugus said she was well-educated on what to expect and how to reduce the chance of having those problems after her gastric bypass surgery. She entirely changed the way she eats.

“A lot of things changed for me psychologically and physically. I physically have a barrier that if I eat too much, I don’t feel good. But psychologically, it just made me really aware of portions and how much we all really eat, and it gave me a perspective on sort of how to eat better,” she said. 

“I knew, for example, that if I overate or took in too many carbohydrates too quickly that I might get something that is called a dumping syndrome, which is essentially really bad diarrhea really quickly, and you just don’t know it’s coming,” Hugus explained. “Or, if I took in too much all at once, it might make me vomit. So that was a challenge at first, because it’s just getting used to your limits and listening to your body.”

Overall, about 1 in 4 surgery patients reported some type of GI problem, compared to 16% of people in the medical/lifestyle group. 

Among the medical/lifestyle group, 25% of people went on during the follow-up period to get surgery, the researchers reported, but an additional analysis indicated it’s unlikely that the later surgery dramatically affected the study’s results for change in glycemic control based on participants’ A1c levels. 

“The spectrum of treatment available to treat obesity in people with type 2 diabetes has been evolving over the years, just like it’s evolving now with the new medications,” Courcoulas said. “And I think that during the period of the study, which was many years … people that weren’t having success controlling their diabetes said, ‘I’m going to go to the next level of treatment.’”

She said that same concept of adding or trying new treatments applies to the introduction of GLP-1 agonist drugs, whose ranks also include semaglutide and tirzepatide – known under brand names Ozempic and Mounjaro. They were FDA-approved for diabetes treatment toward the end of this study’s follow-up period.

The researchers found that people in both the surgical and the medical/lifestyle group started using GLP-1 agonist drugs at similar rates during the follow-up period, and they acknowledge in their published paper that use of those drugs could have influenced the results.

To ask what role these new medications will play in the treatment of obesity and diabetes long-term is the “the million-dollar question,” Courcoulas said.

“We can see that the degrees of weight loss that are being achieved in the trials for these drugs are good and are beginning to approach surgical results,” she said. “When I look at the excitement and interest around these medications, it kind of reminds me of where bariatric surgery was 15 or 20 years ago, where you had short-term studies that showed that, like, unbelievable improvement in type 2 diabetes, and the question back then was, ‘OK, great, but does it last over time?’ And so I think we have the same questions for the medications.”

“What I would say today to a patient is, ‘All treatment options are on the table,'" Courcoulas said. “The foundation is lifestyle, diet, and exercise.”