Bariatric surgery linked to long-term HbA1c reduction, weight loss in type 2 diabetes
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Key takeaways:
- Adults with type 2 diabetes and obesity maintained a 19.3% body weight reduction 12 years after bariatric surgery.
- Diabetes remission was achieved by 12.7% of the bariatric surgery group at 12 years.
SAN DIEGO — Adults with obesity and type 2 diabetes who undergo bariatric or metabolic surgery have a lower HbA1c and greater weight loss than those who did not undergo surgery at 7 and 12 years of follow-up, according to trial data.
In a symposium at the American Diabetes Association Scientific Sessions, researchers presented long-term findings from the Alliance of Randomized Trials of Medicine vs. Metabolic Surgery in Type 2 Diabetes (ARMMS-T2D) trial, which combined data from four randomized trials that assessed outcomes in adults with type 2 diabetes and obesity who underwent bariatric surgery vs. those who did not have surgery. In the study, about 50% of adults who underwent bariatric surgery achieved diabetes remission at 1 year, with 18.2% still having met the criteria for diabetes remission at 7 years and 12.7% having diabetes remission at 12 years. Additionally, the bariatric surgery group maintained a 19.3% reduction in body weight 12 years after surgery.
“Our results show sustained long-term weight loss for surgical patients with obesity and type 2 diabetes,” Anita Courcoulas, MD, MPH, the Anthony M. Harrison professor of surgery at the University of Pittsburgh, said during a presentation. “We also show improved [diabetes] remission with surgery compared to medical treatment.”
Analyzing bariatric surgery’s effect on type 2 diabetes
Sangeeta Kashyap, MD, assistant chief of clinical affairs in the division of endocrinology, diabetes and metabolism at Weill Cornell Medicine New York Presbyterian, and a Healio | Endocrine Today co-editor, discussed how losing 5% of one’s body weight can improve multi-organ insulin sensitivity and beta-cell function, and a weight loss of 11% to 16% can further boost insulin sensitivity. She said metabolic bariatric surgery can induce weight loss to promote these mechanisms and, consequently, the remission of type 2 diabetes, defined as having an HbA1c of less than 6.5% for at least 3 months without the use of glucose-lowering medications. However, Kashyap said bariatric surgery is generally underutilized globally and its effects on adults with a BMI of less than 35 kg/m2 have been understudied.
“We speculate that metabolic bariatric surgery would have favorable impact on induction and maintenance of diabetes remission, leading to lower rates of diabetes complications for our patients,” Kashyap said during a presentation.
In ARMMS-T2D, researchers compiled data from four longitudinal randomized controlled trials designed to assess long-term efficacy, durability and safety of bariatric surgery vs. medical/lifestyle therapy. The trial included 262 adults aged 20 to 65 years with type 2 diabetes, a BMI between 27 kg/m2 and 45 kg/m2 who completed one of the four parent trials and were eligible for long-term follow-up. The cohort included 166 adults who underwent bariatric surgery and 96 who were randomly assigned to intensive medical/lifestyle intervention. Participants attended annual visits where BMI and waist circumference were measured, blood and urine tests were conducted and medication use, diabetes complications, renal events and cardiovascular events were assessed. Adults completed a quality of life questionnaire. The between-group difference in HbA1c from baseline to 7 years was the primary outcome. Secondary outcomes included change in HbA1c, the percentage of adults achieving diabetes remission and differences in weight, BMI, lipids, blood pressure and medication use. Adverse events were collected for up to 15 years.
Bariatric surgery linked to lower HbA1c, maintained weight loss long term
In intention-to-treat analysis, adults who underwent bariatric surgery had a 7.2% HbA1c compared with an 8.2% HbA1c with medical/lifestyle treatment at 7 years (P < .001). At 12 years, the bariatric surgery group had a 7.3% HbA1c compared with an 8% HbA1c with medical/lifestyle treatment (P < .001).
At 1 year following bariatric surgery, about 50% of the surgery group had diabetes remission. At 7 years, diabetes remission remained in 18.2% of the bariatric surgery group compared with 6.2% of the medical/lifestyle treatment group (P = .02). Diabetes remission was observed in 12.7% of the surgery group at 12 years, whereas none of the participants in medical/lifestyle treatment group had diabetes remission (P < .001).
At 7 years, 54% of the bariatric surgery group had an HbA1c of less than 7% compared with 27% of the medical/lifestyle group, and 38% of those who underwent bariatric surgery had an HbA1c of 6.5% or less compared with 17% of those who underwent medical/lifestyle intervention.
“So despite the loss of [diabetes] remission off of medications, glycemic control is sustained in the surgical patients,” Courcoulas said.
Weight loss was also different between the groups, with adults undergoing bariatric surgery maintaining a 19.3% weight loss at 7 years compared with an 8.3% weight loss with medical/lifestyle intervention (P < .001). At 12 years, the bariatric surgery group had a 19.3% body weight reduction since surgery compared with a 10.8% weight loss in the medical/lifestyle group (P < .001).
The percentage of participants who achieved a BMI of less than 25 kg/m2 was 14.4% in the surgery group and 2.7% in the medical/lifestyle treatment group at 7 years. At 12 years, 15.3% of the surgery group had a BMI less than 25 kg/m2 compared with 0% of those receiving medical/lifestyle treatment.
No differences between the groups were observed for BP or LDL cholesterol. The surgery group had higher HDL cholesterol and lower triglycerides than the medical/lifestyle treatment group.
The bariatric surgery group had 20 cases of anemia compared with three in the medical/lifestyle treatment group. There were also 23 incidences of fractures in the surgery group compared with five with medical/lifestyle treatment. The bariatric surgery group had more reports of gastrointestinal events compared with the medical/lifestyle treatment group.
“Decision-making for patient care in people with type 2 diabetes and obesity needs to be individualized and balance the risks and benefits,” Courcoulas said. “Clinicians should consider metabolic surgery as an option to improve diabetes-related outcomes, including for people with class 1 obesity with a BMI less than 35 kg/m2.
More randomized controlled trials needed
Robert H. Eckel, MD, professor of medicine, emeritus, in the division of endocrinology, metabolism and diabetes and in the division of cardiology, and the Charles A Boettcher II Chair in Atherosclerosis, emeritus, at the University of Colorado Anschutz Medical Campus, praised the trial for having a multisite design, a diverse cohort of participants, a long follow-up period and for the “encouraging” association between bariatric surgery and type 2 diabetes remission. Eckel noted there were some limitations, including differences in the study sites and a lack of uniformity on baseline and follow-up data. Eckel also said it was difficult to draw any conclusions from the adverse events report.
“Major adverse outcomes in a small sample like this, even if examined over 7 and up to 12 and 15 years, is not adequate to give us any information about whether CVD, cancer and many other outcomes are ultimately modified by bariatric metabolic surgery,” Eckel said during a presentation.
Eckel added that several questions remain to be answered after ARMMS-T2D. He said studies analyzing which factors predict better outcomes after bariatric surgery need to be conducted. He also said he felt that researchers need to explore which people with type 2 diabetes are more likely to have diabetes remission long term after surgery.
“I believe that randomized controlled trials are needed to document the value [of bariatric surgery] vs. medical lifestyle on controlled outcomes,” Eckel said. “Here, I think we’ve reached the age where a medical comparator is needed. It’s no longer surgery vs. medical lifestyle management, but it’s an integrated combination of two and perhaps three drugs.”
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Kashyap SR, et al. Is metabolic surgery or lifestyle/medical management of type 2 diabetes optimal for long-term health? Long-term outcomes of the ARMMS-T2D randomized trial after 7-12 years of follow-up. Presented at: American Diabetes Association Scientific Sessions; June 23-26, 2023; San Diego (hybrid meeting).
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