Diabetes is strongly associated with socioeconomic status (SES): low income, low education, and low occupational status are all linked to a higher risk for diabetes. Trying to understand the mechanisms underlying the association, Silvia Stringhini from the Institute for Social and Preventive Medicine in Lausanne, Switzerland and colleagues report in this week's PLOS Medicine that a substantial part of it appears to be attributable to chronic inflammation. "Taking together the evidence linking socioeconomic adversity to inflammation and inflammation to type 2 diabetes" the authors write, "it seems reasonable to postulate that chronically increased inflammatory activity in individuals exposed to socioeconomic adversity over the entire lifecourse may, at least partially, mediate the association between socioeconomic status over the lifecourse and future type 2 diabetes risk."
For their study, the researchers focused on 6387 participants who had
provided information on their education level and current occupation
(reflective of early adulthood and present socio-economic status,
respectively) as well as their father's occupation (a proxy for
childhood socio-economic status). In addition, it was known which of the
participants had developed diabetes and when, and whether and when
their blood work had shown signs of chronic inflammation.
They found that cumulative exposure to low SES over the lifecourse
and a downward trajectory from high SES in childhood to low SES in
adulthood were associated with an increased risk of developing type 2
diabetes over the study period. In addition, inflammatory processes,
measured repeatedly through biomarkers in the blood, explained as much
as one third of this association.
"Assuming that our findings reflect a causal association," the
authors say, "our results suggest that tackling socioeconomic
differences in inflammation, especially among the most disadvantaged
groups, might reduce social inequalities in type 2 diabetes."
They suggest that future studies should test interventions that
reduce chronic inflammation, as "(such studies) will be necessary to
determine the extent to which social inequalities attributable to
chronic inflammation are reversible."