Metformin is the most widely used medication for diabetes. In recent years, metformin has attracted attention because it might slow down aging. By direct interference with aging-related processes such as reduced autophagy, the accumulation of DNA damage and inflammation, metformin could reduce the risk of age-related diseases including cardiovascular diseases, cancer and neurodegenerative diseases. This article describes the clinical and translational perspectives of metformin in view of the underlying molecular mechanisms. Similarities and differences between lifestyle interventions such as exercise and therapeutic fasting will be highlighted. Upon a careful evaluation of the known advantages and disadvantages, it can be considered to implement metformin use in specific cases for preventive purposes.