Bariatric surgery provides long-term blood glucose control, type 2 diabetes remission

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, according to a new study supported by the National Institutes of Health. The 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. Results of the study, called the, were published in JAMA and funded by the National institute of Diabetes, Digestive and Kidney Diseases (NIDDK), part of NIH.

“While there are many factors involved, and not all of them are completely understood, bariatric surgery typically results in greater weight loss that effects a person’s metabolic hormones, which improves the body’s response to insulin and ability to maintain healthy blood glucose levels,” said Dr. Jean Lawrence, NIDDK project scientist. “These results show that people with overweight or obesity and type 2 diabetes can make long-term, improvements their health and change the trajectory of their diabetes through surgery.”

The current study is a follow-up that combined data from four independent single-center randomized trials conducted at clinical sites in the United States. 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 involving oral and injectable diabetes medications including insulin, for adults with type 2 diabetes and overweight or obesity. While some participants in the study were prescribed GLP-1 agonists as part of their medical management of diabetes, these drugs were not specifically examined in the study. The 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 surgery and had undergone one of three bariatric surgery procedures. The remaining 96 participants were randomized to the medical/lifestyle management group. The medical/lifestyle interventions have previously been shown effective for weight loss. All participants were between the ages 18 and 65 and had overweight or obesity as measured by body mass index, or BMI. Primary endpoint results were measured at seven years, with continued follow-up through 12 years.

At seven years, participants in the surgery group experienced an average 20% weight loss compared to 8% in the medical/lifestyle group. The surgery group had greater improvements in blood glucose control, measured by HbA1c, with 54% of participants in the surgery group achieving an HbA1c less than 7% compared to only 27% of participants in the medical/lifestyle group. More participants with surgery achieved diabetes remission compared to participants the medication/lifestyle group, and the percent of participants using medications to treat diabetes in the surgery group decreased from 98% to 61%, yet remained largely unchanged in the medication/lifestyle group.

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

Additional exploratory 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 Dr. Anita P. Courcoulas, 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 in the surgery group. Nutritional deficiencies may explain fractures and anemia, underscoring the importance of continued monitoring of people who have bariatric surgery.

“Obesity and type 2 diabetes are complex conditions with many common risk factors and long-term complications,” said NIDDK Director Dr. Griffin P. Rodgers. “This study exemplifies how public investments in obesity and diabetes research can lead to real clinical advances and long-term health benefits for millions of Americans experiencing these conditions.”

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.

Reference: Courcoulas AP, Patti ME, Hu B, et al. Long-term outcomes of medical management vs bariatric surgery in type 2 diabetes. JAMA. 2024; doi: 10.1001/jama.2024.0318.

The NIDDK, part of the NIH, conducts and supports research on diabetes and other endocrine and metabolic diseases; digestive diseases, nutrition and obesity; and kidney, urologic and hematologic diseases. Spanning the full spectrum of medicine and afflicting people of all ages and ethnic groups, these diseases encompass some of the most common, severe and disabling conditions affecting Americans. For more information about the NIDDK and its programs, see https://www.niddk.nih.gov/.

About the National Institutes of Health (NIH): NIH, the nation’s medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit https://www.nih.gov/.