MMP9 and diabetic retinopathy: The MMP-9 (gelatinase-B, macrophage gelatinase or neutrophil gelatinase) mRNA in human urinary sediment has been proposed as a marker of epithelial-mesenchymal transition, which correlates with urinary albumin excretion and blood urea nitrogen and presents a high diagnostic value for diabetic nephropathy, defined by authors as at least 5 years from diagnosis of type 2 diabetes mellitus (T2DM), presence of diabetic retinopathy, elevated albumin/creatinine ratio and absence of other kidney disease (Zheng et al., 2012).