Aging progress and degeneracy of functional activity are mainly attrributed to the decreased DNA repair potential.DNA polymerase (pol) d activity plays an essential role in genome stability by virtue of its crucial DNA replication and repair capacity.To order to clarify the role of DNA pol d in aging progression, we firstly examined the expressions of its catalytic subunit named DNA pol dl in human lymphocytes at different age stages, respectively, and then observed the effect of diseases on DNA pol dl in vivo and of nutriture on its expressions in 2BS cells in vitro.Blood samples from the healthy subjects and patients with diabetes mellitus and coronary heart disease were collected, respectively, for analysis of transcription and protein expressions of DNA pol dl by RTPCR and western blot.2BS cells of PD30 and PD47 were incubated in both normal medium and other mediums of different nutritures for verifying the differential expressions of DNA pol dl.Results showed that the mRNA expression of DNA pol d1 decreased substantially with age and the protein levels were well consistent with gene levels.Furthermore, there were no significant differences in DNA pol d 1 expressions between the groups of healthy individuals and the age matched patients.In addition, DNA pol dl gene expression levels were not affected by nutritional status in vitro.Our findings collectively confirmedand have little bearing on diseases and nutritures.DNA pol dl has great potential for a new biomarker of aging.