Risk variables for the development of obesity and type 2 diabetes

Over the past decades, obesity and type 2 diabetes have been rising at an alarming rate. This rise has been largely considered to be the consequence of a positive energy balance. However, during the period that the incidence in obesity and type 2 diabetes exploded, a plethora of man-made substances have been introduced in our environment. Several of these chemical compounds have the potency to interact with the human hormonal system. These so-called endocrine disrupting chemicals (EDCs) include a large variety of different substances. Parabens, bisphenols and phthalates have in common that they are relatively quickly excreted from the body. Yet, they are used in a wide variety of different every-day products. In this thesis, the primary aim was to determine whether EDCs have an influence on the development of obesity and diabetes. Further, a group of potential risk variables for the development of diabetes ranging further than EDCs was investigated. The studies described in this thesis showed that the Dutch population is ubiquitously exposed to a wide range of parabens, bisphenols and phthalates, and that the exposure has been declining over recent years. Further, we demonstrated the necessity of repeated measurements in prospective association studies, in which we found that exposure to high EDC concentrations was associated with obesity but not type 2 diabetes. When broadening our scope of risk variables for the development of type 2 diabetes, we discovered that many variables showed robust but modest associations, and only a handful were fit for risk prediction.