Bariatric Surgery a Long-Term Winner for Type 2 Diabetes

Patients with type 2 diabetes had better glycemic control and higher rates of diabetes remission over the long term with bariatric surgery compared with lifestyle and medical management in the pre-GLP-1 receptor agonist era, according to a pooled analysis of patient-level trial data.

HbA1c decreased by 1.6% from a baseline of 8.7% in the bariatric surgery group compared with 0.2% from a baseline of 8.2% in the medical/lifestyle group for a between-group difference of -1.4% at 7 years (P<0.001) and -1.1% at 12 years (P=0.002), despite a quarter of the conservative management group crossing over to surgery during follow-up, reported Anita P. Courcoulas, MD, of the University of Pittsburgh, and colleagues.

More patients were free of diabetes after bariatric surgery at both long-term time points: 18.2% versus 6.2% at 7 years and 12.7% versus 0% at 12 years, they noted in JAMA.

Along with those significant advantages, diabetes medication use after bariatric surgery remained lower during follow-up overall compared with baseline and in comparison with the medical and lifestyle intervention for insulin usage (16% vs 56% at 7 years, P<0.001) and for incretin/GLP-1 agonist medications across all annual visits (P<0.001).

Those extra years of remission or very good diabetes control likely had an impact on patient outcomes, although the trials were underpowered for those endpoints even pooled together, co-author Ali Aminian, MD, of the Cleveland Clinic Bariatric and Metabolic Institute, told MedPage Today in an interview monitored by the center’s media relations.

“We would assume that better control of diabetes or remission of diabetes for some time could potentially lower the risk of developing those end-organ, macro-, and microvascular complications of diabetes,” he said. “And that has been shown in previous studies, which is called legacy effect.”

“We know that this is very effective, and this study shows that it’s very durable,” Aminian added. Given the known cost-effectiveness and even cost-savings from bariatric surgery, “it’s very unfortunate that the insurance coverage is still very limited, and only 1% or 2% of patients who are eligible for bariatric surgery get the surgery currently.”

Findings from the pooled analysis help answer one contention made by insurers in limiting access, namely limited long-term evidence for bariatric surgery benefits, noted Thomas A. Wadden, PhD, of the University of Pennsylvania in Philadelphia, and colleagues in an accompanying editorial.

“We believe that the data strongly support recommendations of expert panels, professional associations, and the authors to extend the use and coverage of bariatric surgery to individuals with a BMI [body mass index] less than or equal to 35 who cannot achieve adequate glycemic control with medical/lifestyle intervention,” they wrote.

However, the editorialists noted that the four randomized controlled trials (RCTs) that comprised the pooled analysis “were launched well before semaglutide [Ozempic, Wegovy] and tirzepatide [Mounjaro, Zepbound] were approved for type 2 diabetes and, later, for obesity.”

While the trial results can’t be compared directly, the group pointed out that the “tirzepatide-related reductions in HbA1c compare very favorably with 1-year results in the four original RCTs, with the exception that tirzepatide-treated participants would not meet criteria for diabetes remission because they remained receiving medication.” Also, semaglutide’s impact on major adverse cardiovascular events appears to be similar to bariatric surgery’s impact, they suggested.

However, those drugs don’t have long-term data. “Although clearly challenging to conduct, long-term evaluations are needed that compare bariatric surgery and the new generation of anti-obesity medications on safety, clinical and cost-effectiveness, patient acceptability, and quality of life,” Wadden’s group noted. “In the interim, we encourage clinicians to consider the long-term benefits of bariatric surgery — a vastly underutilized intervention — for individuals with type 2 diabetes not adequately controlled by medical and lifestyle therapies.”

However, Aminian argued, “I don’t see any competition between the two. Both are great options for patients. Some patients would benefit from one, and the others should have access to the other option. So both should be available, and then based on the patient’s condition and shared decision between the patient and the medical team, the decision can be made.”

He suggested that medication could be a good choice if BMI is on the lower side, then surgery preferred for those with a BMI of 50 or greater who need to lose a very large amount of weight, which is “currently achievable only for surgery.”

The pooled analysis included four trials combined to form the Alliance of Randomized Trials of Medicine vs Metabolic Surgery in Type 2 Diabetes (ARMMS-T2D). Of 305 participants in the trials eligible for continued follow-up, 86% enrolled in ARMMS-T2D. Of them, 166 had originally been randomized to undergo bariatric surgery and 96 to medical and lifestyle intervention. During the median 11 years of follow-up, 24 of the control group participants subsequently underwent bariatric surgery.

Notably, sleeve gastrectomy and Roux-en-Y gastric bypass appeared equally effective for HbA1c reduction at both 7 and 12 years, and both were superior to adjustable gastric banding.

The editorialists noted that this is “welcome news,” since gastric banding now comprises only 1% of annual U.S. bariatric surgical procedures, and sleeve gastrectomy, “which accounts for 58% of annual procedures, is easier and safer to perform than Roux-en-Y gastric bypass and is associated with a lower frequency of nutritional abnormalities including anemia, low iron, elevated parathyroid hormone, and vitamin D.”

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