Long-Term Metabolic Outcomes Following Bariatric Surgery: A Systematic Review, Meta-Analysis, and Meta-Regression

Bariatric surgery (BS) has short- and medium-term benefits in improving metabolic syndrome (MetS) components, but its long-term impact remains incompletely characterized. This systematic review and meta-analysis aimed to quantify the long-term effects of BS (≥ 5 years) on fasting blood glucose (FBG), HDL cholesterol, triglycerides (TG), waist circumference (WC), and systolic and diastolic blood pressure (SBP and DBP). A comprehensive literature search was conducted across relevant databases. Eligible studies included randomized controlled trials and observational cohorts reporting pre- and postsurgical metabolic outcomes after at least 5 years of follow-up. Random-effects meta-analyses and meta-regressions were performed. Fifty-four articles (49 cohorts and five RCTs), including 37,840 baseline participants, were analyzed. BS was associated with significant improvements across all outcomes, with effect sizes varying by study design. Pooled estimates ranged from -22.97 to -44.68 mg/dL for FBG, +10.25 to +11.94 mg/dL for HDL, -54.11 to -59.59 mg/dL for TG, -20.55 cm for WC, -7.82 to -9.76 mmHg for SBP, and -4.80 to -6.48 mmHg for DBP. Meta-regression showed stronger effects in patients with higher baseline values. BS provides sustained, long-term improvements in all major MetS components. However, these findings are primarily driven by studies on Roux-en-Y gastric bypass, whereas long-term data on sleeve gastrectomy remain limited. High-quality longitudinal evidence on sleeve gastrectomy is needed to improve the generalizability of these results to contemporary surgical practice.