Although DM has been considered an important risk factor for COVID-19, it seems that in COVID-19 cases with DM who were receiving metformin as an antidiabetic agent, minor lung injury and ARDS have occurred due to the protective role of metformin in AMPK activation and ACE2 phosphorylation, which results in an ACE2 extended half-life and higher circulating ACE2 levels [288]. This evidence concerns the gene ACE2 and diabetes mellitus.