Is inflammation a causal chain between low socioeconomic status and type 2 diabetes? Results from the KORA survey 2000

Low socioeconomic status (SES) is associated with type 2 diabetes. Inflammatory markers like C-reactive protein (CRP) are predictive of diabetes. It is unclear, whether inflammation may be a mechanism linking low SES to type 2 diabetes. In the population-based KORA Survey 2000, 766 men and 710 women aged 55 to 74 years were randomly selected in the Augsburg region (Southern Germany). An index for SES was defined using education, occupation, and income. In women but not in men, increased CRP concentrations were found with lower SES (p < 0.01). This significant trend was no longer observed after adjusting for BMI and waist circumference (p=0.23). Low SES was significantly associated with the age-adjusted odds of having type 2 diabetes both in men (OR; 95%CI: 1.35; 1.14-1.60) and in women (2.01; 1.37-2.96). The risk of having diabetes associated with low SES was only slightly changed after adjusting for CRP, which was itself significantly related to diabetes. In multivariate analyses, adjusting for age, obesity, physical activity, smoking, alcohol intake, and CRP, low SES yielded only a borderline statistical significance in women (p=0.07), whereas no significant association with diabetes remained in men (p=0.14). After CRP was dropped from the full model, there was no change in the OR obtained for low SES (men: 1.30; 0.92-1.83; women: 1.54; 0.97-2.45). Low SES was not related to prediabetes (IFG, IGT), whereas CRP was significantly associated with diabetes precursors. In conclusion, inflammation appears not to play a major role linking low SES and type 2 diabetes in the elderly population.