The pattern of change on all measures of HRQoL following diabetes diagnosis (i.e., a decline in PCS and SF-6D scores, with no change in MCS scores) mirrored the pattern of change for the same measures among diabetes-free DPP participants. This suggests that other factor beyond diabetes diagnosis (e.g., study burden) may have influenced HRQoL over time. DPP treatment burden was substantial. Participants had to provide many biological samples and fill out numerous questionnaires every 6 months for several years. Aging could also have negatively affected HRQoL. The average age at entry into the trial was 51; thus, many of the participants may have begun to experience decrements in their physical capacity that is associated with increasing age. It is know that PCS scores dacline with age and are negatively affected by the onset of complications other than those of diabetes such as arthritis, heart disease, and emphysema. In this context, the declines observed here are similar to those in other studies, albeit which did not focus on diabetes [32 , 33]. In this context, the data partially support the study hypothesis that declines would result from aging, but failed to support that this resulted from the discovery of diabetes per se.