The impact of preoperative therapy with GLP-1 receptor agonists on weight loss and metabolic effects after bariatric surgeries – single-center preliminary study

Glucagon-like peptide-1 receptor agonists (GLP-1 receptor agonists) have become an integral component of obesity management. Although these agents effectively induce preoperative weight loss, their influence on postoperative outcomes following bariatric surgery remains uncertain. This study evaluated the impact of preoperative GLP-1 receptor agonists therapy on weight loss, metabolic outcomes, and safety after laparoscopic sleeve gastrectomy (LSG) and Roux-en-Y gastric bypass (LRYGB). This retrospective observational study included 84 adults with obesity who underwent bariatric surgery between 2023 and 2024 at a tertiary referral center. Patients were divided into two groups: LSG with preoperative GLP-1 receptor agonists therapy (n = 41) and LRYGB with preoperative GLP-1 receptor agonists therapy (n = 43). Anthropometric parameters, percentage total weight loss (%TWL), percentage excess weight loss (%EWL), glycated hemoglobin (HbA1c), lipid profile, blood pressure, and treatment-related adverse events were assessed at baseline and at 3, 6, and 12 months after surgery. Baseline demographic and clinical characteristics were comparable between the groups, although patients undergoing LRYGB demonstrated a slightly more favorable metabolic profile. At 3 months, the LRYGB group achieved significantly greater %TWL (20.12% vs. 18.41%, p=0.023) and %EWL (50.82% vs. 43.48%, p=0.0089), together with greater improvements in HbA1c and lipid profile. By 6 months, between-group differences had diminished, with %EWL remaining significantly higher after LRYGB (67.23% vs. 62.65%, p=0.029), while most other parameters were comparable. At 12 months, no significant differences were observed between the groups in BMI, body weight, %TWL, %EWL, glycemic control, lipid profile, or blood pressure. Gastrointestinal symptoms, predominantly nausea and vomiting, were the most common adverse events. Serious complications were uncommon, and no unexpected safety concerns related to GLP-1RA therapy were identified. Preoperative GLP-1 receptor agonists therapy was associated with substantial weight loss and metabolic improvement before bariatric surgery and demonstrated a favorable safety profile. Early postoperative differences between LSG and LRYGB progressively diminished during follow-up, resulting in comparable clinical and metabolic outcomes after 12 months. These findings support the role of GLP-1RAs as an effective strategy for preoperative patient optimization rather than for improving long-term postoperative outcomes.