Life-course social class is associated with later-life diabetes prevalence in women: evidence from the Irish Longitudinal Study on Ageing

Abstract

This study aimed to investigate the independent and synergistic effects of childhood and adult social class, as well as the effect of social mobility, on type 2 diabetes (T2D) risk in later life. Cross-sectional data from The Irish Longitudinal Study of Ageing (TILDA) (n = 4,998), a nationally representative probability sample of adults aged 50 and older, were analysed. Prevalent diabetes was defined using subjective (self-reported doctor’s diagnosis) and objective data (medications usage and glycated haemoglobin testing). Social class was classified as a three-level variable based on fathers’ occupation in childhood and respondents’ primary occupation in adulthood. A five-level social mobility variable was created from cross-classification of childhood and adulthood social class. Logistic regression was employed to assess the relationship between social class variables and T2D. Mean (SD) age of the sample was 63.8y (9.9) and 46.4% were male. Incidence of T2D was 11.6% of men and 7.7% of women. Some 57.4% of the sample were classified as Manual social class in childhood. Compared to those in Professional/Managerial occupations, belonging to the Manual social class in childhood was associated with an increased risk of T2D in men (Odds Ratio (OR): 1.36, 95% CI: 0.88, 2.10) and women (OR: 2.16, 95% CI: 1.21, 3.85). This association was attenuated in women when controlled for adulthood social class (OR: 1.84, 95% CI: 1.00–3.37), suggesting that the effect of childhood social class may be modified by improving social circumstance over the life course.