Study Is the Largest and Longest Follow-Up Ever to Compare the Effects of Bariatric Surgery Versus Medical Management For People With Type 2 Diabetes  

BOSTON – About 37 million Americans, or one in ten people, have type 2 diabetes (T2D), a chronic metabolic disorder characterized by high blood glucose levels. Consistently elevated blood glucose can damage blood vessels, nerves and organs over time, increasing the risk of developing cardiovascular disease, kidney disease, vision loss and impaired wound healing. While there’s no cure for T2D, it is possible to manage and even reverse the condition through lifestyle changes including diet, exercise, weight loss and carefully controlling glucose levels with medication.

A landmark study conducted at four sites, including Joslin Diabetes Center, reports that people with type 2 diabetes who underwent bariatric surgery achieved better long-term blood glucose control compared to people who received medical management plus lifestyle interventions. Participants who underwent bariatric surgery, also called metabolic or weight-loss surgery, were also more likely to stop needing diabetes medications and had higher rates of diabetes remission up to 12 years post-surgery. The findings, published in JAMA, suggest that weight loss surgery may carry benefits for people with diabetes, even those who are below the traditional BMI threshold of 35 for bariatric surgery. 

“The results of this large, long-running study provide strong evidence that weight-loss surgery provides durable improvement in glucose metabolism,” said site PI M. E. Patti, endocrinologist in the Adult Diabetes section, and director of the Hypoglycemia Clinic at Joslin Diabetes Center. “When we treat diabetes, we're really trying to prevent complications like heart disease, kidney disease, stroke, nerve damage and eye damage. We aren’t just looking to reduce body weight, we also want to improve overall health. This randomized study is an important milestone showing surgery provides sustained improvements in diabetes control.”

The current study combined data from randomized trials conducted independently at Joslin Diabetes Center/Brigham and Women’s Hospital, Cleveland Clinic, University of Pittsburgh and University of Washington/Kaiser Permanente Washington. The original trials, which were conducted between May 2007 and August 2013, evaluated the effectiveness of bariatric surgery compared to intensive lifestyle and medication therapy for adults with type 2 diabetes and overweight or obesity. For the current study, investigators from the four individual studies pooled their data to provide a larger and more geographically diverse data set to evaluate efficacy, durability, and safety of bariatric surgery to treat type 2 diabetes. Follow-up data were collected through July 2022.

In total, 262 participants from the four original studies enrolled in the current study. Of these, 166 were randomized to weight loss surgery. The remaining 96 participants were randomized to participate in medical/lifestyle intervention that had previously been shown effective for weight loss.

Primary endpoint results were measured at seven years, with continued follow-up through 12 years. At seven years, the study showed that:

  • The surgery group experienced an average 20 percent weight loss compared to 8 percent in the medical/lifestyle group.
  • The percent of participants using medications to treat diabetes in the surgery group decreased from 98 percent to 61 percent yet remained largely unchanged in the medication/lifestyle group.
  • 18 percent of participants in the surgery group were in remission—meaning they no longer required medications to control their blood glucose levels—from diabetes, compared to 6 percent of participants in the medication/lifestyle group.
  • The surgery group had greater improvements in blood glucose control, measured by HbA1c (1.6 percent reduction, from 8.7 percent at study entry to 7.1 percent) than the medical/lifestyle group (0.2 percent reduction, from 8.2 percent to 8.0 percent).

The results and differences between groups remained significant at 12 years.

Additional analyses in this study showed that bariatric surgery had important, beneficial effects on HbA1c and weight loss among participants with a BMI between 27 and 34 (within overweight and lower obesity ranges).

“These findings lend important information about the benefit of surgery in people with type 2 diabetes who fall short of the traditional, higher BMI threshold of 35 for bariatric surgery,” said corresponding author Anita P. Courcoulas, MD, chief of Minimally Invasive Bariatric and General Surgery at the University of Pittsburgh Medical Center and lead author of the study.

No differences in major adverse events occurred between the two groups, but there was a higher number of fractures, anemia, low iron, and gastrointestinal events among the surgery group. Nutritional deficiencies may explain fractures and anemia, underscoring the importance of continued monitoring of people who have bariatric surgery.

The study, known as the Alliance of Randomized Trials of Medicine vs. Metabolic Surgery in Type 2 Diabetes (ARMMS-T2D) is supported by cooperative agreement U01DK114156 from NIDDK. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health (NIH).

Co-authors included corresponding author Anita P. Courcoulas, MD, and William F. Gorash, PhD, of University of Pittsburgh; Donald C. Simonson, MD, ScD, and Ashley H. Vernon, MD, of Brigham and Women’s Hospital; Bo Hu, PhD, Gerald J Beck, PhD, and Ali Aminian, MD, of Cleveland Clinic; David E. Arterburn, MD, of Kaiser Permanente Washington Health Research Institute; John M. Jakicic, PhD, of University of Kansas Medical Center; Phillip R. Schauer, MD, and senior author John P. Kirwan, PhD, of Pennington Biomedical Research Center; Sangeeta R. Kashyap, MD, of. Weill Cornell Medicine-New York Presbyterian; David E. Cummings, MD, of University of Washington and VA Puget Sound Health Care System.

About Joslin Diabetes Center

Joslin Diabetes Center is world-renowned for its deep expertise in diabetes treatment and research. Part of Beth Israel Lahey Health, Joslin is dedicated to finding a cure for diabetes and ensuring that people with diabetes live long, healthy lives. We develop and disseminate innovative patient therapies and scientific discoveries throughout the world. Joslin is affiliated with Harvard Medical School and one of only 18 NIH-designated Diabetes Research Centers in the United States.

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