Metabolic and biochemical predictors of glycemic response after bariatric surgery: a scoping review

Background Bariatric and metabolic surgery is one of the most effective treatments for severe obesity and type 2 diabetes mellitus (T2DM), promoting metabolic changes beyond weight loss. However, the biochemical determinants of postoperative glycemic response remain incompletely understood. Methods A scoping review was conducted following PRISMA-ScR guidelines. PubMed/MEDLINE and Scopus were searched for studies published between 2016 and 2025 evaluating metabolic and biochemical variables associated with glycemic outcomes after bariatric surgery. Results Twenty-two studies were included, comprising eight randomized controlled trials and fourteen cohort studies. Bariatric surgery was consistently associated with reductions in HbA1c and significant rates of T2DM remission. Improvements in insulin resistance (HOMA-IR), beta-cell function, and incretin response—particularly GLP-1—were associated with better outcomes. Reductions in inflammatory markers, including IL-6, IFN-γ, and TNF-α, were also reported. Conclusion Glycemic improvement after bariatric surgery is associated with complex metabolic interactions involving insulin sensitivity, incretin modulation, and inflammatory changes. These findings support the role of bariatric and metabolic surgery as a metabolic and immunometabolic intervention, although the descriptive design of a scoping review precludes causal inference.