Diagnostic Evaluation of an Increased Risk of Developing Small Intestinal Bacterial Overgrowth Associated with Glucagon-like Peptide-1 (GLP-1) Receptor Agonists and Dual GLP-1/GIP Receptor Agonists: A Global Retrospective Multicenter Cohort Analysis

Background/Objectives: Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) effectively manage type 2 diabetes mellitus (T2DM) but may impair gastrointestinal motility, increasing the risk of small intestinal bacterial overgrowth (SIBO). Diagnostic evaluation of SIBO commonly involves breath testing and clinical assessment. This study aimed to assess the association between GLP-1 RAs or dual GLP-1/glucose-dependent insulinotropic polypeptide (GIP) RAs are associated with incident SIBO. Methods: We conducted a retrospective cohort study using the TriNetX global database, identifying adult T2DM patients initiating GLP-1 RA or dual GLP-1/GIP RA therapy versus other second-line T2DM agents (OSLT2DM) from 1 January 2006 to 2 December 2024. Patients with major abdominal surgery, connective tissue disorders, gastroparesis, or other high-risk conditions for SIBO were excluded. 1:1 Propensity score matching was applied. Short-term (<1 year) and long-term (up to 5 years) risks were evaluated with Kaplan–Meier curves and univariable Cox models. Results: After matching, 216,173 patients per cohort were analyzed. Short-term analysis demonstrated a higher incidence of diagnostically confirmed SIBO in patients treated with GLP-1 RA/GIP (0.177 per 1000 patient-years) compared to OSLT2DM (0.083 per 1000 patient-years; HR 2.14, 95% CI 1.13–4.07; p = 0.0491). Long-term analysis indicated a non-significant trend toward increased risk in the GLP-1 RA/GIP group (HR 2.02, 95% CI 0.98–4.12), though Kaplan–Meier analysis revealed a sustained divergence (p = 0.017). Conclusions: GLP-1 RA and dual GLP-1/GIP RA therapy are associated with increased short-term SIBO risk. Symptom-driven SIBO breath-test evaluation may be warranted in patients initiating these agents.