Even if the existing literature presents some contradictory data on the effect of MET on testis functions [39,40], our findings are in accordance with studies carried out in diabetic rats in which MET was shown to inhibit the diabetes-induced damages in testicular tissue, increasing plasma levels of T, LH and FSH as well as reducing Sertoli cell [41] and germ cell apoptosis [42]. The gene discussed is PLOD1; the disease is diabetes mellitus.