The relationship between socio-economic status and diagnosed Type 2 diabetes is changing with economic growth in Nanjing, China

Aim: In developed countries, the relationship between socio-economic status (SES) and Type 2 diabetes was positive several decades ago but is now negative. However, in developing societies such as China the relationship remains positive. It is likely that at some stage of economic development the SES–Type 2 diabetes association will become negative in developing communities. This study aimed to examine whether this inflexion is approaching in China. Methods: Two cross-sectional surveys were undertaken in Nanjing, China, in 2000 and 2011. The same sampling approach was used to randomly select participants. Diagnosed Type 2 diabetes was the outcome variable. SES was measured using monthly family average income and divided into thirds. Mixed-effects models were used to calculate the association between SES and Type 2 diabetes. Results: There were 19 861 (response rate, 90.1%) and 7824 (response rate, 82.8%) participants in 2000 and 2011, respectively. A 2.6-fold increase in Type 2 diabetes prevalence was observed from 3.0% (95% confidence interval 2.8%, 3.3%) in 2000 to 8.2% (7.7%, 8.8%) in 2011 (P < 0.01). After controlling for potential confounders, the odds ratios of having Type 2 diabetes decreased from 2.06 (95% CI 1.55, 2.73) and 1.83 (1.40, 2.37) in 2000 to 1.58 (1.23, 2.02) and 1.35 (1.06, 1.74) in 2011 for the higher and middle SES groups respectively, compared with those in the lower SES category. Conclusions: The SES–Type 2 diabetes association remained positive in Nanjing, China, in 2011 but the disparity diminished significantly compared with 2000. These results can inform the delivery of appropriate interventions to people at risk of developing Type 2 diabetes