Glucagon-like peptide-1 receptor agonists improve biomarkers of inflammation and oxidative stress: A systematic review and meta-analysis of randomised controlled trials

Aim To conduct a meta-analysis and systematic review to examine the effects of glucagon-like peptide-1 receptor agonists (GLP-1RAs) on clinical biomarkers of inflammation and oxidative stress in patients with type 2 diabetes. Methods Medline, Embase and the Cochrane Library were searched for randomised controlled trials (RCTs) that examined changes with GLP-1RAs in a priori selected biomarkers of inflammation: C-reactive protein (CRP), adiponectin, tumour necrosis factor-alpha (TNF alpha), plasminogen activator inhibitor-1, interleukin-6, leptin; and of oxidative stress: malondialdehyde (MDA); 8-iso-prostaglandin F2 alpha; and 8-hydroxy-2 '-deoxyguanosine (8-OHdG). Results We included 40 eligible RCTs (n = 6749) with a median follow-up of 6 months, a mean participant age of 53.1 years, 56.3% females, glycated haemoglobin (HbA1c) 55.6 mmol/mol, body mass index 28.8 kg/m(2) and diabetes duration 7.46 years. Analysis of GLP-1RAs versus standard diabetes therapies or placebo revealed significant reductions in CRP, TNF alpha and MDA, and significant increases in adiponectin for (mean difference -0.54 mg/L [-0.75, -0.34]; standard mean difference [SMD] -0.39 [-0.62, -0.15]; SMD -0.84 [-1.61, -0.06] and SMD 0.30 [0.12, 0.49], respectively [95% confidence intervals]). Systolic blood pressure decreased significantly and was significantly and strongly correlated with a reduction in CRP. Homeostatic model assessment of insulin resistance was also significantly correlated with a reduction in CRP, but HbA1c was not. Conclusions There is strong evidence supporting clinically relevant anti-inflammatory and antioxidant effects of GLP-1RAs. This may be used to guide future targeted clinical use of GLP-1RAs and the development of medications seeking to target the cardioprotective properties of GLP-1RAs.