Socio-economic inequality in prevalence of type 2 diabetes among adults in north-west of Iran: A Blinder-Oaxaca decomposition

Background: The aim of this study was to estimate the socio-economic inequality in prevalence of type 2 diabetes among adults in north-west of Iran. Methods: A cross-sectional study was conducted in Ardabil with data from the PERSIAN Cohort Study. Diabetes has been measured by combining self-reported and clinical records. Based on the socio-economic status score, households divided into five quintiles. A multiple logistic regression model was used to examine the association between having diabetes and independent variables and the Blinder–Oaxaca (BO) method was used to decompose the socioeconomic inequality, respectively. Results: The Overall age-adjusted prevalence of diabetes among 20,419 Ardabil’s adults was 14.3% (95% CI: 13.6 to 14.9). The prevalence of type 2 diabetes for the poorest and richest groups was 16.07% and 7.60%, the gap between the poorest and richest groups was 8.47%. The prevalence type 2 diabetes was significantly increasing with increasing in age (OR = 4.05, 95% CI = 3.27–5.02), BMI (OR: 3.10, 95%CI = 1.25–7.68), blood pressure (OR: 2.61, 95% CI = 2.37–2.88), and decreases with higher education level (OR = 0.78, 95% CI = 0.63–0.97). The richest-economic group has lower prevalence of diabetes (OR = 0.73, 95% CI = 0.60–0.88). The decomposition showed that most important factors affecting the difference between poorest and richest group in the prevalence of type 2 diabetes were age (86.1%), years of schooling (46.9%) and having chronic diseases such as hypertension (26.9%). Conclusions: The present study showed that the prevalence of type 2 diabetes was significantly higher among the elderly, women, uneducated, obese, and poor populations. Policies that address people poverty such as increasing job opportunities, increasing the minimum income etc. could reduce diabetes risk for poor people