For example, insulin decreases human macrophage ABCA1 and ABCG1 gene expression in vitro.[29] Animal studies indicate that complications such as nephropathy independently reduce macrophage ABCA1 and increase cellular cholesterol content.[30] Treatment of nephropathy in this study restored ABCA1-mediated cholesterol efflux in macrophages.[30] The present study has the advantage of having matched controls and patients who were drug naive and free of diabetes related complications. This evidence concerns the gene ABCA1 and diabetes mellitus.