Association of Lifecourse Socioeconomic Status with Chronic Inflammation and Type 2 Diabetes Risk: The Whitehall II Prospective Cohort Study

Background: Socioeconomic adversity in early life has been hypothesized to ‘‘program’ ’ a vulnerable phenotype with exaggerated inflammatory responses, so increasing the risk of developing type 2 diabetes in adulthood. The aim of this study is to test this hypothesis by assessing the extent to which the association between lifecourse socioeconomic status and type 2 diabetes incidence is explained by chronic inflammation. Methods and Findings: We use data from the British Whitehall II study, a prospective occupational cohort of adults established in 1985. The inflammatory markers C-reactive protein and interleukin-6 were measured repeatedly and type 2 diabetes incidence (new cases) was monitored over an 18-year follow-up (from 1991–1993 until 2007–2009). Our analytical sample consisted of 6,387 non-diabetic participants (1,818 women), of whom 731 (207 women) developed type 2 diabetes over the follow-up. Cumulative exposure to low socioeconomic status from childhood to middle age was associated with an increased risk of developing type 2 diabetes in adulthood (hazard ratio [HR] = 1.96, 95 % confidence interval: 1.48–2.58 for low cumulative lifecourse socioeconomic score and HR = 1.55, 95 % confidence interval: 1.26–1.91 for low-low socioeconomic trajectory). 25 % of the excess risk associated with cumulative socioeconomic adversity across the lifecourse and 32 % of the excess risk associated with low-low socioeconomic trajectory was attributable to chronically elevated inflammation (95 % confidence intervals 16%–58%)