Evaluating lipid-lowering drug targets for full-course diabetic retinopathy

Implementing lipid control in patients with diabetes is regarded as a potential strategy for halting the advancement of diabetic retinopathy (DR). This study seeks to use Mendelian randomisation (MR) to assess the causal relationship between lipid traits and lipid-lowering drug targets and full-course DR (background DR, severe non-proliferative DR (NPDR) and proliferative DR (PDR)). A two-sample MR and drug target MR to decipher the causal effects of lipid traits and lipid-lowering drug targets on full-course DR, including background DR, severe NPDR and PDR, was conducted in the study. Genetic variants associated with lipid traits and genes encoding the protein targets of lipid-lowering drugs were extracted from the Global Lipids Genetics Consortium and UK Biobank. Summary-level data of full-course DR are obtained from FinnGen. No significant causal relationship was found between lipid traits and full-course DR. However, in drug target MR analysis, peroxisome proliferator-activated receptor gamma (PPARG) enhancement was associated with lower risks of background DR (OR=0.12, p=0.005) and PDR (OR=0.25, p=0.006). Additionally, mediation MR analysis showed that lowering fasting insulin (p=0.015) and HbA1c (p=0.005) levels mediated most of the association between PPARG and full-course DR. This study reveals PPARG may be a promising drug target for full-course DR. The activation of PPARG could reduce the risk of full-course DR, especially background DR and PDR. The mechanism of the PPARG agonists' protection of full-course DR may be dependent on the glucose-lowering effect.