Bariatric Surgery Ensures Superior Long-Term Weight and Glycemic Outcomes: Study
Researchers have found in a new study that patients undergoing metabolic bariatric surgery show better weight loss and glycemic control compared to those who are eligible but opt not to proceed. Long-term postoperative outcomes remain one of the key topics of research because many patients referred for bariatric surgery eventually decide against surgery. The study was published in the International Journal of Obesity by Beatrice L. and colleagues.
This is a retrospective cohort study of 411 adults with type 2 diabetes and obesity referred for metabolic bariatric surgery to University Hospital Ayr, Ayrshire & Arran, from January 2009 to December 2020. The primary outcomes were %TWL and changes in HbA1c over five years. Among the full cohort, 260 patients were female (63%), with a mean age of 48.3 years (SD 8.5) and a mean BMI of 47.4 kg/m² (SD 7.9). The patients were divided into the surgery group and the non-surgery group, in which 225 persons (54.7%) refused or did not undergo surgery despite their eligibility. Changes in annual metabolic and weight-related outcomes were analyzed using mixed-effects modeling.
Results
The baseline demographics, including age, BMI, and sex, were comparable without significant differences between the two groups.
At five years, patients who underwent bariatric surgery maintained a 22.0% TWL, whereas in the non-surgery group, it was only 8.6% (p < 0.001).
The changes in HbA1c in the surgery group demonstrated a drop of 1.0% (95% CI: −1.31 to −0.70), while in the non-surgery group, there was an increase of 0.4% (95% CI: 0.09 to 0.71).
In the surgery group, HbA1c declined by 0.13% per year (95% CI: −0.18 to −0.07; p < 0.001), while it increased by 0.11% per year in the non-surgery group (95% CI: 0.05 to 0.17; p < 0.001).
%TWL decreased slightly, at a rate of -1.31% per year (95% CI: -1.73 to -0.88; p < 0.001) in the surgery cohort, while the nonsurgery arm increased by 1.11% (95% CI: 0.66-1.55; p < 0.001) per year, reflecting continued weight gain.
This study shows that patients who undergo metabolic bariatric surgery have substantially greater and more durable weight and glycemic improvements than those patients who choose not to undergo surgery. These data emphasize the need for robust alternative interventions, such as intensive lifestyle therapy, pharmacologic weight-loss agents, and structured diabetes education, for patients who do not receive surgery.
Reference:
Leyaro, B., Howie, L., Ali, A. et al. Metabolic bariatric surgery pays off: a longitudinal analysis of weight loss and HbA1c changes in real-world patients data in the West of Scotland. Int J Obes (2025). https://doi.org/10.1038/s41366-025-01956-6
