Impact of bariatric surgery on glycaemic and metabolic outcomes in people with obesity and type 2 diabetes mellitus: A meta‐analysis

Abstract Aims Bariatric surgery is a widely adopted intervention for managing obesity and improving glycaemic control in patients with type 2 diabetes mellitus (T2DM). This meta‐analysis evaluates the impact of bariatric surgery on glycaemic and metabolic outcomes, including fasting blood glucose (FBG), postprandial glucose (PPG), HbA1c, C‐peptide, HOMA‐IR and fasting insulin levels. Materials and Methods Comprehensive search of PubMed, Scopus, EMBASE and Web of Science was conducted from inception to March 2025. Eligible studies were pooled using a random‐effects model to calculate weighted mean differences (WMD) or standardized mean differences (SMD) with 95% confidence intervals (CIs). Heterogeneity was assessed using I 2 statistics, and publication bias was evaluated using funnel plots and Egger's tests. Results Thirty‐nine studies with 3855 participants were included. Bariatric surgery resulted in significant reductions in FBG (WMD = 3.461; 95% CI: 2.740–4.182, p < 0.001), PPG (WMD = 6.153; 95% CI: 4.298–8.007, p < 0.001) and HbA1c levels (WMD = 2.085; 95% CI: 1.561–2.608, p < 0.001). Modest but non‐significant improvements were observed in C‐peptide (SMD = 0.358; 95% CI: −0.043 to 0.759, p = 0.075) and fasting insulin (SMD = 1.593; 95% CI: −0.392 to 3.577, p = 0.104). Significant reductions in HOMA‐IR levels (WMD = 2.480; 95% CI: 1.010–3.950, p = 0.009) were noted. High heterogeneity was observed across most outcomes. Publication bias was detected for FBG and HbA1C, while it was undetected for the rest of the outcomes. Conclusions Bariatric surgery significantly improves glycaemic and metabolic outcomes in obese patients with T2DM. These findings support its integration into diabetes management pathways, offering a promising approach for long‐term disease control and complication reduction. Further research is needed to evaluate long‐term outcomes and mechanisms.