Cardiovascular risk reduction with glucagon-like peptide-1 receptor agonists is proportional to HbA1c lowering in type 2 diabetes: An updated meta-regression analysis incorporating FLOW and SOUL trials

Abstract

Aims: To evaluate relationships of cardiovascular and kidney outcomes with glycemic or bodyweight reductions in randomised placebo-controlled trials of glucagon-like peptide-1 receptor agonists (GLP-1RAs), incorporating data from FLOW and SOUL trials. Materials and Methods: PubMed and EMBASE were searched up to 22 August 2025 for placebo-controlled randomized trials of oral or bolus-type, subcutaneous GLP-1RAs reporting major adverse cardiovascular events (MACE; a composite of cardiovascular death, myocardial infarction, and stroke) in adults with type 2 diabetes. The primary outcome was MACE; secondary outcomes included heart failure (HF) and kidney outcomes. Random-effects meta-analyses were followed by meta-regression evaluating associations with HbA1c and bodyweight reduction. Results: A total of 73 263 individuals were included from 10 trials (ELIXA, LEADER, SUSTAIN-6, EXSCEL, Harmony Outcomes, PIONEER 6, REWIND, AMPLITUDE-O, FLOW, and SOUL). GLP-1RAs reduced MACE by 14% (hazard ratio: 0.86; 95% CI: 0.82 to 0.91; p <0.001), as well as hospitalisation for HF and the composite kidney outcome (both p <0.001). Meta-regression showed that every 1% extra reduction in HbA1c corresponded to a 27% lower HR for MACE (p = 0.015; R2 = 0.61). While HbA1c reduction was not significantly associated with secondary outcomes, the directionality was consistent with MACE. Bodyweight change was not associated with any of the analysed endpoints, including MACE (p = 0.13; R2 = 0.21). Conclusions: HbA1c reduction, not bodyweight change, was significantly and proportionally associated with MACE risk reduction. HbA1c lowering may serve as a useful surrogate for the cardiovascular improvements associated with GLP-1RAs in type 2 diabetes.