Microvascular effects of glucagon-like peptide-1 receptor agonists in type 2 diabetes: a meta-analysis of randomized controlled trials

Results with GLP1-receptor agonists (GLP-1RA) on microvascular complications of diabetes are contrasting. In trials designed for cardiovascular outcomes, both liraglutide and semaglutide were associated with a relevant reduction in the incidence and progression of nephropathy. On the other hand, in the same trials, semaglutide was associated with an increased progression of retinopathy, and a similar trend was observed for liraglutide. This meta-analysis is aimed at assessing the effects of GLP-1RA on retinopathy and nephropathy. A Medline search for GLP-1 receptor agonists (exenatide, liraglutide, lixisenatide, albiglutide, dulaglutide, or semaglutide) was performed, collecting all randomized clinical trials with a duration > 11 weeks, enrolling patients with type 2 diabetes, and comparing a GLP-1 receptor agonist with placebo or any other non-GLP-1 receptor agonist drug. Of the 113 trials fulfilling the inclusion criteria, 78 and 62 did not report information on retinopathy and nephropathy, respectively. Treatment with GLP1-RA was not associated with a significant increase in the incidence of retinopathy (MH-OR [95% CI] 0.92 [0.74-1.16]. p = 0.49). In subgroup analyses, GLP1-RA were associated with a lower risk of retinopathy in comparison with sulfonylureas. Cases of macular edema were reported only in nine trials with no sign of increased risk. GLP1-RA reduced the incidence of nephropathy with respect to comparators (MH-OR [95% CI] 0.74 [0.60-0.92]. p = 0.005). This difference was significant versus placebo, but not versus any class of active comparators. GLP1-RA appear to reduce the incidence and/or progression of nephropathy and to have no specific effect on retinopathy-with the notable exception of semaglutide, which could have a negative impact on the retina.