Introduction

The life expectancy in many countries is projected to exceed 85 years by 2030.1 Globally, one quarter of the population is expected to be in their sixties or older in 2050.2Nonetheless, the unprecedented longer life expectancy heralds a staggering number of people living with age-related diseases and considerable burdens on the social, economic, and healthcare systems worldwide. There is a pressing need to combat the challenges posed by age-related diseases and increase the health span of humans. However, while age-related diseases can often coexist, current delivery of health services and research efforts have continued to deal with the diseases ineffectively in an insular fashion.3 In contrast, mechanisms that account for the phenotypes of old age, such as impaired metabolism, dysregulated immune profile, and abnormal DNA methylome, have been shown to be the underlying determinants of many chronic diseases.4 Therefore, modifying the mechanisms of aging directly seems to be a more productive approach to fundamentally curb the growth of chronic diseases.
Although aging has been traditionally considered an irreversible process, encouragingly, a growing number of studies have indicated that metformin and rapamycin, two drugs that have been used extensively to treat type 2 diabetes (T2DM) and as an immunosuppressant respectively, have the potential to stall aging and delay the onset of age-related diseases. In this review, we survey a selection of articles about metformin and rapamycin to give a glance of the anti-aging mechanisms that have been studied with these two drugs and their extent of effectiveness. Finally, remaining questions and concerns are highlighted to guide future anti-aging research.