Peripheral blood leukocytes were chosen for analyzing the expression of SIRT1 and diabetes-related genes in pregnancies with GDM and those with normal glucose tolerance (NGT) since these cells are able to reflect pathological changes occurring in different tissues of the body: their use has been recommended in exploratory studies where metabolic tissues are not available, as in the case of pregnant women [27]. The gene discussed is SIRT1; the disease is diabetes mellitus.