Effects of bariatric surgery to induce weight loss and HbA1c reduction shown to persist at 12 years

Abstract

Bariatric surgery has increasingly become an important strategy to induce and maintain weight loss and diabetes remission. A recent study presented at the American Diabetes association [1] meeting has provided additional evidence on the long-term effects of bariatric surgery on the effects of weight maintenance and HbA1c reduction.

The findings presented were from the Alliance of Randomized Trials of Medicine Versus Metabolic Surgery in Type 2 Diabetes (ARMMS-T2D), a prospective, controlled trial with the largest cohort and longest follow-up of bariatric surgery reported to date. ARMMS-T2D included data from 262 people with overweight or obesity and type 2 diabetes randomized in any of four US studies that compared the outcomes of 166 patients who underwent bariatric surgery with 96 patients who served as controls and had lifestyle and medical interventions for weight loss and glycemic control. The prospective analysis was derived from four independent randomized studies that compared bariatric surgery with lifestyle and medical intervention in people with type 2 diabetes and overweight or obesity: STAMPEDE (N = 150); SLIMM-T2D (N = 88); TRIABETES (N = 69) and CROSSRAODS (N = 43). All of these studies started more than 10 years ago and therefore did not incorporate evidence derived from the use of novel, potent anti-obesity therapy that is available today.

The study showed that people who underwent bariatric surgery (gastric band, sleeve gastrectomy, or Roux-en-Y gastric bypass) had a mean 1.6% reduction in HbA1c levels from baseline at 7 years and a 1.4% reduction at 12 years—compared with a mean HbA1c reduction of 0.2% and 0.3% respectively, among controls who underwent lifestyle and medical interventions only. Average weight loss from baseline to 7 and 12 years were 19.9% and 19.3%, respectively, compared with 8.3% and 10.8%, respectively, among controls. Roux-en-Y gastric bypass appeared to have the best rates of patients achieving both lower HbA1c levels and more weight loss, followed by sleeve gastrectomy and gastric banding. While the investigators cautioned that the study was underpowered to reliably compare individual surgical procedures, these findings interestingly were comparable to that observed in the adequately powered By-Band-Sleeve study—which also showed superiority of gastric bypass surgery. The efficacy of weight loss of ~20% with bariatric surgery appears to be comparable with the efficacy of some of the novel incretin-hormone receptor agonists therapy for weight loss such as semaglutide (Ozempic/Wegovy) and tirzepatide (Mounjaro) and so forth, but these effects from bariatric surgery were observed at 7 and 12 years, which makes these findings remarkable. Further studies are required to incorporate the combination/synergistic effects of weight loss pharmacotherapy with bariatric surgery.

Importantly, the study also showed notable rates of two adverse events associated with bariatric surgery: a 14% incidence of bone fractures compared with a rate of 5% among controls, and a 12% incidence of anaemia after surgery compared with a rate of 3% among controls. These are recognized adverse effects which highlights the importance of assessing bone health and anaemia risks before and after bariatric surgery. In addition, the study observed significant reductions in triglyceride levels and increased high-density lipoprotein cholesterol levels, compared with controls. However, 22% of surgery patients experienced abdominal pain compared with 10% of controls, and 7% experienced dysphagia compared with no cases among the controls.