Bariatric surgery outperforms medical management in long-term diabetes control

People with type 2 diabetes who underwent bariatric surgery achieved much better long-term blood glucose control compared to people who received medical management plus lifestyle interventions, according to a new study published in JAMA, or Journal of the American Medical Association, and funded by the National institute of Diabetes, Digestive and Kidney Diseases, part of The National Institutes of Health.

In addition, participants who underwent bariatric surgery, also called metabolic or weight-loss surgery, were more likely to stop needing diabetes medications and had higher rates of diabetes remission up to 12 years post-surgery. Pennington Biomedical's Dr. John Kirwan and Dr. Philip Schauer were among the lead investigators for the 12-year study, titled "Alliance of Randomized Trials of Medicine vs Metabolic Surgery in Type2 Diabetes," or ARMMS-T2D.

This is the largest and longest running study of its kind, and provides the key insight that metabolic surgery provides better long-term remission of type 2 diabetes over standard management of the disease. As Principal Investigator of this multicenter trial, I am so proud of the outstanding team effort that brought together scientists from Pennington Biomedical, Cleveland Clinic, Harvard, Pittsburgh and Seattle to collaborate and contribute to this milestone study."

Dr. John Kirwan, MSc, PhD, Executive Director and the George A. Bray, Jr. Endowed Super Chair in Nutrition, Pennington Biomedical Research Center

The study combined independent single-center randomized trial data from four centers in the U.S. – Cleveland Clinic, Joslin Diabetes Center/Brigham and Women's Hospital, University of Pittsburgh, and University of 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 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 common bariatric surgery procedures: sleeve gastrectomy, gastric bypass and gastric banding. The remaining 96 participants were randomized to the medical/lifestyle management group. Participants in the lifestyle interventions received treatments that have previously been shown to be 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 percent weight loss compared to 8 percent in the medical/lifestyle group. The surgery group had greater improvements in blood glucose control, measured by HbA1c, with 54 percent of participants in the surgery group achieving an HbA1c of less than 7 percent compared to only 27 percent 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 percent to 61 percent yet remained largely unchanged in the medication/lifestyle group.

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

"We are pleased to have taken part in this landmark study, and these results further reinforce the confidence we have in metabolic surgery," said Dr. Schauer, Director of the Metamor^TM Metabolic Institute at Pennington Biomedical. Dr. Schauer, a metabolic surgeon, performed the surgery on these patients while at his former position at the Cleveland Clinic. "For patients with type 2 diabetes and obesity, who are at serious risk of heart attack, stroke, premature death, or diabetes complications, metabolic surgery, especially gastric bypass or sleeve gastrectomy, is safe, well established and an effective life changing option for many."

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).

No differences in major adverse events occurred between the two groups, but there were more incidences of fracture, anemia, low iron, and gastrointestinal events in the surgery group. Nutritional deficiencies may explain fractures and anemia, underscoring the importance of vitamin supplementation and continued monitoring of people who have bariatric surgery.

Study participant Judge Parker, who exhibited the same diabetes and obesity present in his family history, underwent bariatric surgery in December 2008 by Dr. Schauer. Since the surgery, and with regular check-ups, he now weighs 195 pounds, dropping from 306 pounds prior to the surgery. Additionally, Parker is diabetes free, is not taking any diabetes medication and has an A1C level of 5.6 percent.

"The surgery was my lifesaver," Parker said. "I was on diabetes medicines and insulin, but I mostly remember I had a hard time getting around, I got tired and simply didn't feel good. Now, I'm rearing to go, over 100 pounds lighter and free of diabetes, sleep apnea and lower blood pressure."

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 NIH National Institute of Diabetes and Digestive and Kidney Diseases, or NIDDK.

"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 represented a long-term collaboration of researchers from a variety of esteemed research centers and clinics, including Pennington Biomedical Research Center, the University of Pittsburgh's Department of Surgery, the Joslin Diabetes Center's research division, Harvard Medical School, the Department of Quantitative Health Sciences and the Department of Surgery at the Cleveland Clinic, Kaiser Permanente Washington Health Research Institute, Brigham and Women's Hospital's Division of Endocrinology and its Division of General & GI Surgery, Diabetes and Hypertension, the University of Kansas Medical Center's Department of Internal Medicine, Division of Physical Activity and Weight Management, the Division of Endocrinology, Diabetes and Metabolism at Weill Cornell Medical Center, the Department of Medicine at the University of Washington and VA Puget South Health Care System.