Effects of genetically proxied statins on diabetic nephropathy and retinopathy: a Mendelian randomization study

There is no reliable causal evidence for the effect of statins on diabetic nephropathy (DN) and diabetic retinopathy (DR), and the results of previous observational studies are contradictory. Genetic variants linked to low-density lipoprotein cholesterol (LDL-C) from a UK biobank genome-wide association study and located within a 100kb window around HMGCR were used to proxy statins, comparing with PCSK9 inhibitors (control). DN and DR genome-wide association study summary statistics were obtained from the FinnGen study. Secondary MR analyses and NHANES cross-sectional data were used for validation. Drug-target Mendelian randomization (MR) was applied to investigate the association between the genetically proxied inhibition of HMGCR and PCSK9 with DN and DR, p < 0.0125 was considered significant after Bonferroni Correction. To triangulate the findings, genetic variants of whole blood-derived targets gene expression (cis-eQTL) and plasma-derived protein (cis-pQTL) levels were used to perform secondary MR analyses and data from the National Health and Nutrition Examination Survey were used for cross-sectional analysis. Genetically proxied inhibition of HMGCR was associated with higher risks of DN and DR (DN: OR = 1.79, p = 0.01; DR: OR = 1.41, p = 0.004), while no such association was found for PCSK9. Secondary MR analyses confirmed these associations. Cross-sectional analysis revealed a positive link between statin use and DR incidence (OR = 1.26, p = 0.03) and a significant negative association with glomerular filtration rate (Beta = - 1.9, p = 0.03). This study provides genetic evidence that genetically proxied inhibition of HMGCR is associated with increased risks of DN/DR, and this effect may not be attributed to their LDL-C-lowering properties. For patients with diabetic dyslipidemia, PCSK9 inhibitors may be a preferable alternative.