Effects of GLP-1 Receptor Agonists and Dual GIP/GLP-1 Receptor Agonists on Inflammatory and Metabolic Biomarkers in Type 2 Diabetes: A Systematic Review and Meta-Analysis

Background: Glucagon-like peptide-1 receptor agonists (GLP-1RAs) and dual GIP/GLP-1 receptor agonists improve cardiovascular outcomes in type 2 diabetes mellitus (T2DM), but their effects on inflammatory and oxidative biomarkers are not fully defined. Materials and Methods: We searched PubMed, Ovid MEDLINE, Scopus, Web of Science and the Cochrane Library from inception to 19 February 2026 for randomised controlled trials (RCTs) in adults with T2DM comparing a GLP-1RA or dual GIP/GLP-1 agonist with placebo or active therapy, and reporting C-reactive protein (CRP or high-sensitivity CRP [hs-CRP]), interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), malondialdehyde (MDA) or adiponectin. Random-effects meta-analyses were conducted using standardised mean differences (SMDs). Results: Forty-one RCTs were included. GLP-1RAs significantly reduced CRP/hs-CRP (27 studies, 1991 participants; SMD −0.37, 95% CI −0.59 to −0.14) and MDA (3 studies, 272 participants; SMD −0.98, 95% CI −1.65 to −0.30), and increased adiponectin (16 studies, 1327 participants; SMD 0.30, 95% CI 0.13 to 0.46). Pooled effects on IL-6 (17 studies, 1068 participants; SMD −0.14, 95% CI −0.37 to 0.10), TNF-α (16 studies, 1164 participants; SMD −0.25, 95% CI −0.61 to 0.12) and MCP-1 (7 studies, 450 participants; SMD −0.27, 95% CI −0.58 to 0.03) were not statistically significant, although MCP-1 decreased in sensitivity analyses. Across biomarkers, heterogeneity was moderate to high. Two tirzepatide RCTs (562 participants) showed a significant reduction in IL-6 (SMD −0.28, 95% CI −0.47 to −0.09) and a non-significant trend towards lower CRP/hs-CRP. Conclusions: In adults with T2DM, incretin-based therapies consistently lower CRP/hs-CRP, reduce oxidative stress (MDA) and increase adiponectin, while effects on IL-6 and TNF-α are more variable. These data support a selective anti-inflammatory and metabolic regulatory profile of GLP-1–based therapy, but heterogeneity and limited data for some biomarkers warrant cautious interpretation and further mechanistic studies. Trial Registration: PROSPERO number: CRD420261321430. © 2026 John Wiley & Sons Ltd.