Socioeconomic inequalities in type 2 diabetes comorbidities in different population subgroups: trend analyses using German health insurance data

While socioeconomic inequalities in the prevalence and management of type 2 diabetes (T2D) are well established, little is known about whether inequalities exist in the prevalence and the temporal development of T2D comorbidities. Previous research points towards expansion of morbidity in T2D as depicted mainly by a rising trend of T2D comorbidities. Against this background, and using German claims data, this study aims to examine whether socioeconomic status (SES) inequalities exist in the rates and the temporal development of T2D comorbidities. Since previous research indicates varying risk levels for T2D prevalence in the population subgroups: working individuals, nonworking spouses and pensioners, the analyses are stratified by these three population subgroups. The study is done on a large population of statutory insured individuals with T2D in three time-periods between 2005 and 2017. Predicted probabilities of three comorbidity groups and the number of comorbidities were estimated using logistic and ordinal regression analyses among different income, education and occupation groups. Interaction analyses were applied to examine whether potential SES inequalities changed over time. The study showed that neither the cross-sectional existence, nor the temporal development of T2D comorbidities differed significantly among SES groups, ruling out SES inequalities in the prevalence and the temporal development of T2D comorbidities in Germany. In men and women of all examined population subgroups, predicted probabilities for less severe cardiovascular (CVD) comorbidities, other vascular diseases and the number of comorbidities per individual rose significantly over time regardless of SES, but little if any change took place for more severe CVD comorbidities. Another important finding is that the population subgroup of nonworking spouses had markedly higher predicted probabilities for most of the examined outcomes compared to working individuals. The study indicates that the expansion of morbidity in T2D in Germany does not appear to be SES-dependent, and applies equally to different population subgroups. Yet, the study highlights that nonworking spouses are a susceptible population subgroup that needs to be focused upon when planning and implementing T2D management interventions.