Our study involving healthy postmenopausal females established that mammographic breast tissue density was lower in cases of more intensive stimulation by glucose of reactive insulinemia and glucose-induced glyoxalase I activity in bood mononuclears as well as in women with higher concentrations of circulating CD90+stem cells. Conversely, the density tended to increase in those with higher ratio of glucose-induced generation of reactive oxygen species in mononuclears. Our data point to possible mechanisms of increased density as a breast cancer factor when concomitant with relative predominance of progenotoxic effect of glucose and lower CD90+stem cells levels which are believed by some authors to be capable of suppressing the growth of certain tumors.