Development of Comorbidities in Type 2 Diabetes: Morbidity Expansion or Dynamic Equilibrium?

Background Different hypotheses have been proposed about the future development of morbidity associated with the temporal improvement in life expectancy. However, many studies have focused on general morbidity while testing these hypotheses. In type 2 diabetes (T2D), one of the most prevalent chronic diseases, research points towards an increasing prevalence over time with a simultaneous increase in life expectancy among this population. While morbidity compression in T2D can thus be ruled out, it remains unclear whether morbidity expansion or dynamic equilibrium applies, which could be the case with a decrease in personal disease burden despite increasing prevalence. Against this background, this study aims to examine how the prevalence of T2D-related comorbidities is developing over time. Methods Using claims data of a large statutory insurance provider in the state of Lower-Saxony, Germany, the period prevalence of nine T2D-related comorbidities was examined for the time periods 2005-2007, 2010-2012, and 2015-2017 in 240241, 295868, and 308134 individuals with T2D, respectively. The temporal development of comorbidities was examined by logistic regression analysis. The change in the number of comorbidities over time was examined by ordered logistic regression. Analyses were stratified by gender and three age groups. Results Over the three time periods, age-adjusted predicted probabilities for more severe cardiovascular diseases (CVDs) decreased in men and women with T2D while those for less severe CVDs and other vascular diseases such as retinopathy, polyneuropathy any nephropathy increased significantly in all subgroups. Among all subgroups, the predicted probability of having more comorbidities over time also increased significantly. Conclusions Despite differences in the way CVDs are developing, the results are in favour of the morbidity expansion hypothesis for this population. Further research is needed to examine the reasons behind the observed trends. Key messages The developement of comorbidities in individuals with type 2 diabetes points towards morbidity expansion among this population. Future studies should examine whether the change is socioeconomic status, medication use and lifestyle risk factors are contributing to these trends.