In particular, testing a larger number of Nrf2−/− mice after challenging with high fat diet or after inducing diabetes would be useful to characterise the behaviour of the nonlinear biomarkers in the presence of an extensive oxidative stress load or a metabolic disease, and testing the biomarkers in a knockout model for the eNOS enzyme would be useful to elucidate better the role of NO. This evidence concerns the gene NOS3 and diabetes mellitus.