A vertical-horizontal approach to examine social inequalities in early onset type 2 diabetes in the German workforce through occupational sector, education and income

Early onset type 2 diabetes (T2D) is increasingly recognized as a significant public health concern, leading to more severe complications and a greater decline in quality of life compared to T2D diagnosed later in life. This can have a profound impact on the workforce. Social status-whether assessed vertically through levels of income, education or job position or horizontally through occupational groups-can play a critical role in the risk of developing early onset T2D. While research focusing on vertical socioeconomic inequalities related to T2D is abundant, there is currently no study that combines both vertical and horizontal perspectives to explore vulnerable groups. We aim to combine the vertical and horizontal approaches to examine vulnerable groups within the employed population regarding early onset T2D. Using data from the largest statutory health insurance provider in the state of lower Saxony, Germany for the year 2019 "Allgemeine Ortskrankenkasse Niedersachsen" (AOKN), we examined education and income inequalities in early onset T2D among nine occupational sectors using logistic regression analyses (N = 365059). Age and gender adjusted prevalence rates as illustrated by predicted probabilities were displayed to compare rates of early onset T2D among different education and income levels and occupational groups. Regression tree analysis was used to examine intersectionality between the vertical (levels of income and education) and the horizontal (occupational sector) dimensions in order to determine the most vulnerable groups. Both vertical and horizontal inequalities in early onset T2D exist within the employed population. On the one hand, disparities in education and income were present across various occupational sectors. On the other hand, significant differences in T2D prevalence could be observed within the same education and income levels across different sectors. Notably, affiliation to occupational sector was the primary factor influencing vulnerability to early onset T2D, followed by educational attainment. Individuals with low education working in the "Transport, logistics, protection and security" and "Health, social work, teaching, and education" sectors were among the most vulnerable. It is important to simultaneously examine both vertical and horizontal dimensions of inequalities to identify vulnerable groups within the workforce. Future research should adopt this approach while also exploring other populations and health outcomes.