2-Deoxy-D-glucose (2-DG) and dehydroepiandrosterone (DHEA) have been hypothesized to extend lifespan via mimicking calorie restriction (CR). Activation of sirtuins has been proposed to contribute to life extension of CR by increasing intercellular levels of NAD(+) in several organisms. However, it is unclear whether 2-DG and DHEA may affect intracellular NAD(+) levels and human sirtuin 1 (SIRT1) activities. Here, using human fibroblast Hs68 cells we showed that 2-DG increased intracellular NAD(+) levels in both time- and concentration-dependent manners. 2-DG also dose-dependently increased SIRT1 activities and the lifespan (measured as the cumulated growth curve of population doubling levels) of Hs68 cells. In contrast, DHEA at non-cytotoxic concentrations (?50 ?M) did not significantly affect NAD(+) levels, SIRT1 activities or the lifespan of Hs68 cells. These results suggest that 2-DG extends the lifespan of Hs68 cells by increased NAD(+) levels and SIRT1 activities, and that 2-DG has a potential as a CR mimetic.