The predominant function of ACE2 is to metabolize Ang II to Ang 1–7, reduce inflammation and oxidative damage, and counteract the harmful effects of the ACE-Ang II-AT1 pathway; therefore, ACE2 performs multiple salutary biological functions in several diseases, such as heart failure, myocardial infarction, hypertension, kidney diseases, acute lung injury, diabetes and AD [44–47]. This evidence concerns the gene ACE2 and diabetes mellitus.