Can present biasedness explain early onset of diabetes and subsequent disease progression? Exploring causal inference by linking survey and register data.

Diabetes is a major cause of morbidity, disability, mortality and health care resource use. The increasing prevalence of diabetes may therefore have dramatic future consequences for western societies. Diabetes entails a significant self-management component and it has previously been estimated that people with diabetes provide about 95% of their own care. Despite increased focus, self-management skills including basic knowledge acquisition, problem solving and setting realistic goals are often not mastered. The main contribution of this paper is to provide evidence that the heterogeneity in self-management and health outcomes amongst diabetes patients is partly attributable to individual differences in time-inconsistent preferences in terms of present biased behaviour. Using a unique data set consisting of survey data from 2014 merged with registry data on a sample of 79 chronically ill patients, we present empirical evidence that present biased individuals are more prone to onset of diabetes at an early age, and have a poorer prognosis after diagnosis. Furthermore, we conclude that present biasedness has a casual effect on the onset and management of diabetes.